Correct Voltage for Gents Pulsynetic Master Clock

[Lincolnhill]

I have just finsihed refurbishing a Gents Pulsynetic Master Clock and was wondering what the correct voltage is for this style of clock. I thought I should ask before accidentally connecting too much voltage and damaging the coils.

In case it matters, it is a master clock with one slave dial attached.

The only information I was able to find online said 12V to 24V but that is a pretty broad range.

Any help would be appreciated.

Michael

 

[RODALCO]

The Gents master and slave clocks usually have a series system for all the dials which runs at around 180 to 200 mA's.

If a 12 Volt or 24 Volts supply is used an appropiate series resistor shall be used in series with the powersupply to the clock line.

Most Gents coils are 4 Ohms, (from memory) at 200 mA the voltage across the coil is 0.8 Volts. ( U=I x R ).

In you case, the coils from the gravity mechanism 0.8 Volts,
The clock dial, 0.8 Volts and the slave dial 0.8 Volts. Total 2.4 Volts.

If you use a 12 Volts DC supply then:
12-2.4=9.6Volts
at 200 mA's
R = 48 Ohms.
From P= I² x R, the power rating of the resistor shall be 1.92 Watts

A 48 Ohms resistor is non E12 series. So a 47 Ohms 5 Watt ceramic resistor from Jaycars, Dick Smiths or any electronics shop will do. Cost less then 0.5 dollar.

You can try a 68, 56 or 47 ohms Resistor.
sometimes when only a few clocks are in series it may well work fine at 150 mA's which will reduce the noise every 30 seconds.

Regards

Raymond

 

[Hans Vrolijk]

Michael,

The Gents Pulsynetic system is designed to run on 220 mAmps. So the voltage is not important, but the current is. There should be a adjustable resistor in the clock to set the current.

 

[Lincolnhill]

Thank you Hans and Raymond,

If you can please excuse my electrical ignorance I have some additional questions. I am going to explain what I have done first then questions second.

1) I tried two "D" cell batteries in series to create 3 volts. I have no idea how many milliamps this creates. With this attempt the magnets did not charge sufficiently.

2) Next I tried two "D" cell batteries in series while also in parallell with one 6-volt lantern battery. The clock has been running and charging nicely for about 30 minutes. I believe this creates a total of 6-volts and by having the "D" cells in parallell with the lantern battery it generates additional amperage.

First question, how can an electrical novice armed with a simple Radio Shack volt meter determine how many amps I am putting to the magnets? I would assume the section of the volt meter dial labeled mA's is the answer?

Second question, using commonly available household batteries what do you recommend using? Especially since one of my "D" cell batteries just exploded , I assume this is not the recommended sequence.

Third question, my clock was in a terrible state when I acquired it. Other than the coils, there was no wiring present. I have some original style cloth covered wiring, but need to know where to use it to attach the coil of the slave clock to the movement itself. If you could point me in the right direction it would be appreciated.

Thank you again for all of your assistance. This is such a neat and different clock than the typical one I get to work on. While it was only running about a half hour, it was very rewarding to here it trigger every 30 seconds.

Michael

 

[K Reindel]

Michael,

First, one should never put two battery stacks together at different voltages. I guess you found that out. You've probably ruined your 6 volt lantern battery as well, and you might consider replacing it.

If your Radio Shack meter can measure the resistance of the coils, you can then calculate the current by taking the voltage (eg a fresh lantern battery is 6 volts) and divide that by the resistance of the coil you measured.

Your welcome to contact me at ken@kensclockclinic.com if you want to go through some examples or explanations, or other ways of measuring the current.

Ken

 

[RODALCO]

Michael, Yep, don't put a 3 Volts and 6 Volts battery in parrallel.

As you found out the 6 Volts battery was trying to charge up the 3 Volts battery and a large current would have flown between the batteries until one blew up.

It should have done no damage to your masterclock though.

If you have a multimeter you probably have a mA and a Amp range on it.
If you are experimenting and not sure what amps are flowing in the circuit, use the Amps range first. This has an internal fuse in it rated at 10 Amps.
The mA range is usually fused at 300 mA or 0.5 Amps.

You are on the right track by using D cells which are 1.5 Volts each.
If at 3 Volts the clock didn't run properly or the magnet didn't pull in then put an extra D cell in series to make the Voltage 4.5 Volts.

Easiest is to get a 3 or 4 way D cell holder from an electronics shop.

The ammeter goes in series with the circuit.

So: ( POSITIVE from batt. ) to ( AMPS terminal on meter ) to ( Common terminal on meter ) to ( Master clock circuit in ) to ( Masterclock cct out ) to ( NEGATIVE from battery ).

A D cell battery can give a current of more 10 Amps for a short time, the cell will heat up rapidly as it's internal resistance increases, It also will be exhausted very quickly.

Because the clocks only take around 220 mA for a very short time, a set of 3 D cells should last for a reasonable amount of time.

Raymond

 

[Tom McIntyre]

It may be difficult to see the current with an ordinary ammeter. It is an irregular pulse from the contact closings. You are better off calculating as shown in the earlier posts.


misspelled contact

 

[Hans Vrolijk]

It may be difficult to see the current with an ordinary ammeter. It is an irregular pulse from the contact closings. You are better off calculating as shown in the earlier posts.


In the good old times the Gent engineers put a penny coin between the contacts of the master clock to keep the circuit closed when measuring the current.

 

[Lincolnhill]

Thank you all for your quick and thorough replies.

I am off to purchase some new batteries and will continue experimenting soon.

Thanks again,

Michael

 

[Tom McIntyre]

The resistance of the coils is undoubtedly the primary source of impedance with the low frequency operations. However, these are coils and the dc impedance is not the same as the active impedance in operation.

There is also a fairly significant breakdown surge that causes most of the pitting on the contacts of these clocks. I tried putting a shunt diode on my Synchronome, but I could not tell much difference. I don't have an oscilloscope anymore to look at these things.

 

[Lincolnhill]

Good Evening,

I just downloaded a copy of the Gent's of Leicester installation and repair manual. It contains a wealth of information and now that I have a much better understanding of Volts, Amps, Resistance, etc. it makes sense.

According to the manual, the master clock movement (that drives the pendulum) has a resistance of 33 ohms. In addition, the slave unit has a resistance of 4 ohms (which is consistent with Rodalco's post). Therefore it appears that my clock has a total resistance of 37 ohms which combined the required current of .22 amperes equates to a voltage requirement of 8.14 volts. This sounds about right as it was operating (weakly, but operating) on a 6-volt lantern yesterday.

All that said, I am still struggling on where to install the slave clock wires. As the slave clock operates at only 4 ohms, I assume I will have to install the appropriate resistor so I do not burn out the coil. But where to connect the two leads remains a mystery.

Any guidance would be appreciated.

Thanks again,

Michael

 

[K Reindel]

On the vibrating and rotary motor SWCC models, the inductance (AC impedance of the coil) actually comes into play somewhat. The "time constant" of these coils is on the order of about 20 milliseconds (ms) or less. The motors apply current to the motor for a period somewhat longer than this every cycle, so this AC impedance therefore lowers the current a little vs. what you'd expect from the DC measurement of resistance alone.

On the single shot self winders (eg once per second or once per minute), the coil is turned on for significantly longer, on the order of 150ms, possibly up to 500ms or more. In this case the AC impedance plays a much smaller role in determining the current and the DC dominates.

This AC impedance is one of the reasons to avoid using diodes across the coils in the vibrating and rotary motors (stick with the damping resistors). The diode will cause the coil to hold its magnetic field longer than it should after the commutator opens the circuit, which may keep it from operating at its optimum.

Ken

 

[RODALCO]

I had a look on Google for you too, but unable to find an exact schematic which details the Gents wiring loom.

I'm pretty sure the slave dial does go in series with the 30 seconds contact.
Perhaps someone with a working Gents masterclock can trace the wiring and provide you with a drawing.
I haven't got a Gents masterclock at home, but a Favag, Bürk, Moser Baer, Inducta and ECS. which all use the 24 Volts alternating polarity one minute impulse system as used in continental Europe.

An interesting link though regarding gents clocks is attached below.

http://west-penwith.org.uk/misc/gent.htm

Good luck and keep us posted when it all works.

Raymond

 

[Edwardo]

HI Lincolnhill,
I have been following this thread for the past couple of days

This is the easy way to sent up your clock

I suggest you use a 9 or 12 volt DC plug pack style power supply
Make sure it is rated at 1 amp or higher.
3 amps is better because you will probably want to add extra slave clocks later

You should not need to buy any resistors

Inside you clock case is a large wire wound resistor (normally on the left)
It is an oblong shaped item, light grey in colour
It has a black knob on it with a small silver locking screw in the middle.
You need to loosen this screw to allow the knob to move

The wiring is very simple

The positive (+) of the supply goes to one side of the contacts in the master clock
The other contact goes to the master clock coil, then to the fist slave then the next and so on in a daisy chain formation.
The last wire coming from the last slave goes to the negative (-) of the power supply

This type of wiring is called series wiring and is simply a circle coming out of the power supply, going through all the clocks and back in to the supply

After you have wired all this up, set your meter to milliamps and put the two probes between the two contacts on the master clock

The contacts will try to close but you must force them open (a second pair of hand is always useful)
Adjust the sliding resistor on the left up or down until you get a reading of .22 amps (220 milliamps)

If you use a 12 volt supply the resistor knob should be near the bottom

Once you have set this resistor hand tighten the little screw in the knob ane the clock is set.

You will not burn out any coils with just 12 volts DC

Before you invest in a power supply you may want to test it with a car battery

If you are still stuck send me the clock serial number and I will dig out the circuit diagram for it

Hope this helps

Edd

 

[Lincolnhill]

Good Evening Ed,

Eureka! It is now so obvious.

As I mentioned earlier, my clock was missing all of the wiring when I acquired it. The part you describe, the large grey wire wound resistor is no longer present. I had not missed it because I did not know it should have existed.

That said, your description of wiring the slave and master clock in sequence is extremely helpful. I had been wondering where on the movement the slave was to attach, but as you describe it attaches within the power supply circuit and not the movement itself.

OK - Here is where I am at:

1) The clock is running and "winding" nicely on 4 "D" cell batteries set in series and therefore producing 6 volts. It will not wind on 3 "D" cell batteries or 4.5 volts. According to my calculation and the information in the users manual, the gravity coils draw 33 ohms which when combined with a 18 to 22 mA resistance should require 5.94 to 7.26 volts. So my 6 volts seems both reasonable and not too high as to damage the coils.

2) I then acquired a generic 10 ohm, 10 watt ceramic resistor from Radio Shack. When installed in series with the 6 volt battery pack the slave clock advances nicely. Not too powerful, not too little. If I install two resistors in series then I get nothing.

As my clock is missing the adjustable resistor Ed describes, I am going to try everything in series with no resistor and see what happens. Will keep you all posted.

Again, the good news is that everything is ticking merily and seems to be reseting the gravity arm properly. I adjusted all of the tolerances back to factory specs last night and the gravity arm triggers much better than a day ago. I think we are getting there!

Michael

 

[Lincolnhill]

OK, everything is wired in series with 6 volts. The gravity arm is resetting with the same force as before and the slave clock is doing nothing?? It is getting some power as the magnet barely moves, but it is not advancing.

The adventure continues...

Michael

 

[Lincolnhill]

One more update for the night...

6 volts - gravity arm works perfectly, slave clock nothing.
7.5 volts - gravity arm works perfectly, slave clock nothing.
9 volts - gravity arm works perfectly, slave clock nothing.

On its own...the slave clock advances nicely at 3 volts and weakly at 1.5 volts. I am sure I am missing something simple, but that is for tomorrow. Maybe the electrical impulse is too short and the gravity arm is cutting it off before the slave has time to react

Michael

 

[Tom McIntyre]

My Synchronome needed a bit more current to make the slave go than to make the master with its local slave operate. The only issue I can see with the variations in current we are discussing is that you may get a bit of a spark when the contacts break.

I have a power supply with a 12 volt battery backup in my basement and I think about 29 ohms series resistance.

Here is the page on my synchronome it is not the same but is pretty similar to the Gents.

 

[Edwardo]

Michael
Forget the resistor and the idea of running the clock from “D” cells

“D” cells, because of their design will not last more then a few weeks

The problem you describe indicates there is enough voltage but not enough current (AMPS)
The batteries referred to in the manual were large lead acid batteries that could deliver many amps. (similar to car batteries).

“D” cells can’t give the sort of service the clock needs

If you run this type of clock off “D” cells you will find that within a week the batteries will start to fail and probably leak nasty stuff all over the place

For what you are trying to do you don’t need the resistor to start with.
All that it is doing is sucking more power (amps) out of the circuit

Think of amps as the power water travels through a garden hose
And the clock coils as empty beer cans on a wall

If you point the hose at the empty beer cans the water blows them away
This is because the water is coming out powerfully

If you reduce the flow through the hose pipe by standing on it,
the water pressure drops and there is not enough power to knock the cans off the wall

The resister you are using is working like your foot on the pipe

So what you need to do is turn up the pressure (amps) to get the coils to operate
The only way to increase the Amps is to use a heaver duty power supply

Your “D” cells can’t deliver this type of power, so after time they will self destruct

It is not possible to burn out the coils in your clock with the type of batteries you are using
Nor is it possible with a small 12v dc 3 amp power pack

The worst that will happen is the coils will start to warm up if they are energised for a long period of time (30 seconds or more)

You are more likely to destroy the batteries or supply first

Current Diagnostic
If the current is to low the master clock or slaves won’t work

If the master clock works, but slave does not, the current is still to low

If the master clock works and so does the slave, BUT the slave misses pulses or jumps on extra minutes the current is to high or very sightly to low

You really need to invest in a power supply that is at least 1000ma (1Amp) 12vDC output

Worry about the resistor later

Edd

NOTE

BTW
Tom is correct about the spark issue
It will eventually burn out the contacts (a few years)

The old fix for this used resistors and capacitors. This worked very well.

The new fix is some 2 cent rectifying diodes that can be bought from any electronic parts supplier (radio shack??)

Simply wire one across every coil, (only one on the master clock across the terminal block on the main movement)
Make sure that the stripe (on the diode) faces the (+) side of the circuit

There has been a lot posted on this forum regarding the rights and wrongs of spark suppression

I use diodes because they are cheap and they work
They are small enough to hide behind other clock parts and do not alter the clocks originality in any way that may devalue it.

In your case, Michael I wouldn’t worry about the diodes until you have the supply sorted

Nice clock Tom

 

[eskmill]

Michael.
My copy of the Chloride Gent Pul-syn-etic instruction manual is in agreement with the numbers you quoted on the 29th taken from the Gents of Leicester manual. Your calculation based on the 33 ohms electromagnet coils in the master clock and the 4 ohm coils for each slave clock is correct. It should operate on 8.14 volts (33+4 ohms times 0.22 amperes) optimally and ideally should continue to function with a source voltage as low as 6.29 volts. (37 ohms times 0.17 amperes)

Because you state that the slave dial fails to register suggests that the slave may not be properly adjusted.

There's other possibilities too. The electromagnet coils in the slave may have shorted turns or may have a shunt resistor in parallel with the electromagnet coil both would lower the 4 ohms resistance. (somewhat difficult to measure with an ohmmeter)

Too, your slave might possibly be one designed to use with a Synchronome and those slaves operate at about 330 milliamperes.

If it helps, I just tested two Pulsynetic slaves. Each operate reliably at 1.1 volts or just slightly above the 170 milliampere minimum current.

I believe you are on the right track and it's OK to operate your Gents system from six "D" size alkaline flashlight cells arranged in series to provide just a little over 9 volts.

Keep us posted.

 

[Lincolnhill]

Good Evening All,

I think we are on the right track now.

Taking Ed's advice I returned (for the fourth consecutive day, they know me by name now!) to my neighborhood Radio Shack and picked up a 12V, 1500 mA power supply. As this is more powerful than I think I needed, I connected it to the clock in series with the slave clock and two 10 ohm, 10 W resistors. The gravity arm worked perfectly, but the slave still faltered.

So I set off to adjust the slave and low and behold after I backed the pressure off of the driving spring and off she went.

It is now two hours later and the clock and slave have been operating perfectly and even better are within 5 seconds of my Timex. Who would have guessed that a clock that was so buggered up would have been adjusted so closely.

As for arcing...a small flash is visible but to be honest my Standard Electric master clock that has been running flawlessly for the last eight years arcs alot more and has not needed anything other than a regular battery changing. That said, I plan on looking into a rectifying diode simply to expand my electrical knowledge a bit more. I will let you all know if it improves the arcing.

Thank you all for your guidance. This has been a perfect example of the benefit of this message board. Hopefully I will be able to help out someone else in the future on a topic that I am knowledgable about.

Thanks again,

Michael

 

[eskmill]

Michael.
Let's do the math:
You have the 33 ohm master clock electromagnets plus the 4 ohm slave electromagnet and two ten ohm series resistors. 33+4+10+10=57 ohms
57ohms times 0.22amperes=12.54 volts. Thus it appears that 12 volts is close to optimal.

Now, let's hope your Radio Shack 12 volt 1.5 amp DC supply has some regulation. Typically they don't and the unloaded voltage is often much higher; 1.4 times or as high as 16 or 17 volts.

Try inserting a milliammeter in series to measure the current with the master contacts shorted with a coin as suggested. It should not be much more than 250 milliamperes.

Let us know.

 

[Edwardo]

ICKMILL

You are correct in suggesting that the slave may not be a Gents.
If it is a Gents, it may not be the correct type of slave for this master clock

I would not suggest tempering with the slave movement at this stage as that could add further complications to the problem

We are all assuming that Michael’s clock is a C7 and not a C6 or a P.O.36

Maybe Michael can post some photos so we can confirm that we are all talking about the same thing

The cells referred to in the Gents manual are lead acid batteries which have a different chemistry to standard “D” cells

The main reason I do not recommend “D” cells is that they are not designed for this sort of application and will soon break down and leak.

“D” cells are designed for a slow constant discharge not an almost short circuit every 30 seconds

 

[eskmill]

I would prefer to debate off line with Ed via eMail or by P.M. regarding the use of dry cells to provide power for the Gent pulsynetic system in a hobby-collector environment.

Unfortunately, Ed isn't registered so Private Message isn't possible and his eMail address isn't stated so I have no choice but to defend my recommendation of the use of dry cells openly.

I have a different view on the use of dry cells which are, in my opinion, quite satisfactory for the Gent clock used by the hobby-collector.

True, under heavy continuous closed circuit dry cells will heat and deplete.

However, the Gent Pulsynetic system in question consumes only 220 milliamperes for less than a tenth of a second. That occurs 120 times per hour or an accumulated duration of less than 12 seconds or a three-hundredth part of an hour.

A standard zinc-carbon "D" size dry cell has a capacity of 150 amp-hours. One-three hundredth part of the 150 amphour capacity is a very small part of the dry cell's amp-hour capacity.

The alkaline "D" flashlight cell is said to have a capacity of about 340 amp-hours.

Either, I believe, in a series of six, is a completely satisfactory source for the simple Gent master clock with one slave.

I agree that other direct current sources are entirely satisfactory and may offer special advantages but realistically, there exists few known large Gents systems in remaining in daily use which of course would be provided direct current from a supervised storage battery system.

 

[Edwardo]

ECKMILL, sorry for misspelling your name in the last post

I am not trying to debate the rights and wrongs of anything here

Your knowledge on this forum is legendary and well respected

I am trying to help someone out, with what I believe is the correct information

When I did my training with Gents Chloride in London during the early1980’s, the failings of dry cell batteries were made very clear to us


Regarding the resistance:

Everyone is quoting 33 ohms for this master clock

This is correct for a C7 master clock (actually between 32.4 & 35.2 in my experience)
A C7 master clock has a built in dial and slave
The resistance quoted is for the total unit

A C6 is the same clock without the dial

My C6 has two 15 ohm coils in series that make 30ohms not 33 ohms (however the real value is 29.7 ohms)

This information is in your manual on page 2

In the good old days Gents service techs carried around nice AVO meters to measure the current and resistants
The problem was most of these meters were not very well calibrated

I still have mine


This didn’t really matter as long as the clocks ran OK, after all the lead acid batteries had loads of power in reserve

One other point, you mentioned:

You said “I have a different view on the use of dry cells which are, in my opinion, quite satisfactory for the Gent clock used by the hobby-collector.”

The problem is that the Gents clock was designed as an industrial machine not a hobby clock
That’s why I recommend a more suitable power supply rather then change the batteries regularly

Don’t take this information the wrong way; I am just trying to help




BTW
I was under the impression that I was registered and have been since last year.
Also quite a few people have contacted me by clicking on my user name??

I do not wish to debate this subject as your mind is already made up and I worked for Gents

But I would be very interested in your opinion regarding an ITR clock that I have recently acquired

I will post my questions later

 

[RODALCO]

Here is a schema from a Gents Master clock.
It clearly shows that all clocks are in series.

Courtesy of Ebay U.K.

Regards, Raymond

 

[Edwardo]

Here is a schema from a Gents Master clock.
It clearly shows that all clocks are in series.

Courtesy of Ebay U.K.

Regards, Raymond

Gents offered provisions for parallel connection
The slaves were a bit different and had an advance button on them, not unlike the late model Magneta
They ran on 24vDC to 48v DC
The master clock had no resistor in it, but looked the same as the C6/C7

 

[ged]

Hello All, I have a Gents Master Clock and a seperate 9in Slave, I believe the Clock Dial inside top of Master Clock is actually a Slave. I found mine ran on a 9volt battery but was so heavy on batteries I bought a power unit to run it off the main Electricity Supply. I think I had it set at 8.5 Volts. It was so Noisy the wife threatened to leave home or set about it (The Clock) or me both with an Axe. I have it mounted on the wall in my garage and dont run it at all. In fact i have given it to my Eldest daughter and she will take it to her new home when she finishes her work tour in Germany. PS, I also have a GENTS Slave that works on alternate reverse Polarity, incompatible with mine, Anybody need one?. Regards, Ged.

 

[Lincolnhill]

As requested, here is a photo of my now restored and running clock. Next up is to clean and wax the case.

Thanks again for all of the help,

Michael

 

[Lincolnhill]

Oops, forgot to mention that it is serial number 1481 so I believe it is pre-1930's.

 

[John UK]

Your clock serial number 1481 would date from early 1915. My clock s/n 1455 is dated December 1914.

John

 

[Edwardo]

Lincolnhill

Your clock is a very early C7

Are you sure your Clock is # 1481 and not clock #1418?

I have notes on a clock #1418 that was made on the 16 July 1914 for a company in Glasgow, Scotland

I believe it was for export to U.S.A

It seems like too much of a coincidence

I would love to see some pictures of the movement and slave to confirm its date

Edd

 

[Lincolnhill]

Good Morning Ed,

Good question. The wood case is stamped with the serial number #1481 on the top front edge of the case, but the small paper tag that is located on the inside right side of the case has a handwritten serial number of #1418.

I just assumed that one of the two had an accidental transposition.

In either case I will take a couple of photographs of the movements and try to post them in a couple days.

Any insight you may have on my actual clock would be much appreciated.

Thanks,

Michael

PS. The clock is still running and advancing nicely.

 

[John UK]

In 1914, Gents used as an agent in Glasgow, George Edwards of 92, 97 Buchanan Street, Glasgow. I don't know if they were used exclusively at that date, since Gents had many agents over the years.

 

[Lincolnhill]

As requested, here are the photos of my clock's moverment and the slave dial. Please let me know if you need anything else to help identify it.

Thank you,

Michael

 

[Hans Vrolijk]

As requested, here are the photos of my clock's moverment and the slave dial. Please let me know if you need anything else to help identify it.

Thank you,

Michael

Lucky you!
This is a very early Gent indeed. see graph.

 

[Daniels Clock]

Not sure if anyone is watching this post as it was started some time back. Thought I would let you know it was useful in getting my Gents pulsynetic ticking again. Serial number 6584 dated 14 Feb 1949.

 

[harold bain]

Hi, Daniel, welcome to the message board. Glad you found our archives useful.

 

[Mickyblueeyes]

Hi Daniel, your post and looking at the posts in this thread reminded me i needed to get my clock working again too.

Mine is serial No 6613 dated 11th march 1949

I got mine to remind me of where i started, my first job in 1978 was to test and set S type movements as an apprentice at Gent in Leicester, the S type was the standard movement used in the pulsynetic clock sytem.
I must have liked it as i stayed a further 14 years!.

 

[Daniels Clock]

Hi Mickey, with your experience I'm sure you will find the job more straight forward than I did. The wiring incorporated 2 sets of chokes and resistors and 3 sets of points. I took the movement out of the case because I couldn't fathom out where the cables were going. Think I have it right now its undergoing time trials. I've got the lap top running next to it with 4 stop watches. Its lost 4.5 seconds in two hours so have added 2 more air rifle pellets to top of pendulum.

One question for anyone out there, watching the contacts (in the dark) there is no flash across them. Does this confirm I have choke / resistor wired correctly?
Regards
Daniel

 

[Dave C]

Hi All

I am new to all this but . . . I have a Gent Master Clock that was used in a Electro Mechanical Exchange. Being from a Telco background I have managed to get it working but I very much doubt that the method I used is correct.

I need to know how to connect the dial into the circuit. So far I have put a relay in parallel with the coil that operates the gravity lever? The contacts connect between the supply and the dial coil thus the dial steps in sync with the lever reset coil.

Can anyone point me in the right direction please, see the attached pic's as well. I am also in the process of tidying the wiring.

BTW. my clock has serial number 15236

 

[Edwardo]

Hi Dave C
Welcome aboard
A photo of the main movement would be helpful
Your clock was made in 1976
I don’t have a circuit diagram for your particular clock, but the electrical principle is as follows:

The voltage from the positive side of the battery/power supply enters the clock case.
It then goes through the pilot dial, through a variable resistor and then to the main contacts (every 30 seconds). From there it goes to the two large coils that reset the gravity arm, and then back to the minus side of your power supply
Adjust the variable resistor so the current through the circuit is 220ma upping or downing the voltage appropriately

I would suggest 12vdc as a starting point

I noticed that you’re clock has additional slave units to administer different outputs.
These would possibly be 10 second and six second depending on the how they are wired.
If you are intending to use this clock in a domestic environment I suggest you exclude these slaves from the circuit, due to the noise they will emit.
Kind regards
Edd

 

[Dave C]

Hi Edd

First of all many thanks for your reply, i will be putting some effort into working on the unit over the weekend. I will also report back as soon as I have made progress.

I have found that 12 Volt DC works best for this particular unit. It was originally wired for 48 Volt but by by passing the tho 330 Ohm 30 Watt resistors the clock is now happily ticking along on 12.

I found the date card inside the clock this afternoon and according to that it was made during Desember of 1975. A bit of background on this particular clock. It was used at a local telephone exchange where I worked as a learner technician during 1988. Later the exchange was upgraded? to an electronic exchange. The senior technician in charge of the exchange since it's opening had the privilege of getting this clock as reward for his duties there. He passed away a couple of years ago and since I also used to visit his house frequently I was given the clock by his son.

For some reason I can not post the picture here tonight

 

[Dave C]

A photo of the main movement can be found here http://www.congate.co.za/100_1223.JPG

 

[Dave C]

Hi Again Edd

Ok I have done the wiring as per your instruction but then nothing happens, none of the coils activate, upon further investigation I found that there is no resistance reading between "Time Dial" and "-" (open circuit) which leads me to believe that there was a modification made to the clock to operate the exchange equipment.

I will however be looking into this a bit and report back as soon as I have something.

Dave C

 

[cbara]

Re: Correct Voltage for Gents Pulsynetic Master Clock / Exchange Master Clock

Have "Chloride Gent" No:15358 (dated 22/09/1976) in exactly the same Exchange Master configuration.

Outside of case is also marked ST-BY. Is clearly set up for Exchange Battery voltage of 48v DC and runs happily at that voltage under the required 200 mA.

Bridge terminal "R.M" to term "Time Dial' apply DC supply to "+" and "-" and movement should run along with slave dial as well as 6 sec and 10 sec 'counters'.

This variant must be unique to South Africa ("SAPO") as only have seen one other, 3 in total.

 

[Dave C]

Hi

Ok I have since my last post succeeded in getting the clock to work, and also managed to do so with 12 volt instead of the 48 originally required.

When you open the case on the right hand side inner wall of the clock, just below the advance retard switch there should be two rather large green resistors. Just bridge these and the clock will happily run along on 12 Volt.

I also had a problem that the gravity arm would not reset properly. I fixed that with a little adjustment of the catch.

Would like to get my hands on some slave dial's though

 

[cbara]

Hi, Slaves will be hard to find as almost all had been thrown away as they have no use as clock, or had quartz movemments fitted. (If you are in RSA contact me off-line as have a set of complete set-up instructions for the movement, which you are welcome to a copy of)

 

[boockpj]

Hi all
I got hold of 2 x Gent of Leicester clocks that were used in an Electro Mechanical Exchange. I bought it to use the cabinets for display cabinets (for my diecast car collection), but after opening it (both were full of dust on outside and I could not see the inside), I've decided that this is something special and I can't break this up. I don't have a clue how to get this going again. I'm not familiar with volts, circuits, watts, etc..etc..
Manuals are still there. I will read through all your messages and will let you know if I'm winning.

 

[boockpj]

Me again....
Serial numbers for the 2: 15233 and 15234 (both with a date = 2/12/1975)