Power to the points!!

[nicebutdim]

Hi all, I've had a look through everywhere and can't find anything about this, so I'm posting a call for help! Finally getting some track down (yipee) and now getting to the points for the station area. Two of them are electrified motors, which after help from here before, are now working as they should. I'm sorting out the wiring to the motors, and came across an old Capacitor Discharge Unit from Gaugemaster, is it possible (or moreso safe) to use it through a reversing switch to operate lgb point motors? It has a 16v ac input and a dc output, with what a remember from the peco point motors, quite a thwack of discharge power. Has anyone here tried using one before? Would it give enough power to operate 2 lgb motors at the same time?
Many thanks in advance, Tim

 

[minimans]

I don't know if it will work or not but LGB makes there own Cap discharge unit for EPL operated points and signals I use one on my system and it does work exactly as described. these come up on eBay often and usually sell for between $25 & $50...................

Use to increase the available energy to operate switches and signals under adverse conditons.
Features
The Booster is connected between the transformer AC Output and the 51750 control box. The EPL Booster can supply up to eight 51750 control boxes. LED lights, red, green and yellow, show the operating state of the unit

 

[beavercreek]

Well Paul that is very clear ...and in triplicate

 

[minimans]

Well Paul that is very clear ...and in triplicate

OOOOOOOOOOOOOOOOOOOOp's Thank heavens for the edit button button button..................

 

[stockers]

Odd - my knowledge of electrickery is limited but newer LGB point motors are AC. I dont see how a capacitor does AC?

 

[minimans]

Odd - my knowledge of electrickery is limited but newer LGB point motors are AC. I dont see how a capacitor does AC?

Actually there DC! but use a halfwave AC to provide the power! top half of the wave is one direction lower half the other...............

 

[stockers]

True Paul - but even so - can you use a capacitor discharge sysytem on that?

 

[minimans]

True Paul - but even so - can you use a capacitor discharge sysytem on that?

I believe the boost is provided on the outgoing current to the point motor which is in effect a DC current so I guess this is how they do it, but now I'm going to have to open up my box to see what's inside!!!

 

[ntpntpntp]

To use a CDU with a two wire DC motored system such as EPL, the activating switch needs to swap the polarity of the CDU output. So you'd probably use a double pole double throw centre-biased switch DPDT (ON)OFF(ON), wired the same way as you'd wire a normal latching DPDT to swap track polarity . So the outer pairs of switch terminals cross-wired and connected to the CDU output, with the centre pair of switch terminals connected to the point motor.

That's different to a typical CDU application (eg. Peco solenoid point motors) which is a three wire approach (2 coils plus common return). Here you only need a single pole double throw switch SPDT (ON)OFF(ON) and no changing of polarity is required. One side of the CDU is wired to the centre switch terminal, the outer switch terminals to the point motor coils, and the other side of rthe CDU to the point motor common.

Would be easier to draw a piccie but I'm on my little linux netbook which is a pain to use with drawing software etc.!

 

[nicebutdim]

That's exactly the idea I was having, using a dpdt switch wired as a reversing switch. In theory I can see it working! I just had a look on the Gaugemaster web site and it says you can use up to 24v ac as a supply, so I thought of the LGB 5 amp transformer that I have, but gaugemaster say to only use up to a 2.5 amp supply!?! I thought a unit would only pull as much current as required upto the max output of the transformer, rather than being limited by the current supplied. I may have to contact Gaugemaster to see if this is true, or if they mean it pulls a max of 2.5 amp.

 

[minimans]

I use a 5amp 24v AC transformer for my EPL and a booster on the points furthest away from the shed. I've not had a problem since using the booster. It's important that you use a good power source and good heavy wire to the system or it wont work reliably even with a booster or CDU most problems I see with people using EPL are caused by lack of power or too small a gauge of wire.

Anyway I pulled my LGB booster apart and I can't see how it works!! I'm usually pretty good at following a circuit to see how it works but this has me stumped, there is a clear bypass path around the board from the inlet to outlet side? so what triggers the actual boost? we need an electronics guy here not a car guy at this point!!

 

[nicebutdim]

I think even though there is a bypass around the sides, the capacitor charges using some of the components, drawing its current until charged, then (maybe) when the point motor is operated, the voltage drops, prompting the capacitor to discharge its charge into the circuit to 'boost' the power to the motor. That's my theory anyway, and if you can follow it at least I know I'm not alone on my own little planet
Anyway, thanks for opening up your unit miniman, it does give me bit more of an insight into how some other units operate and how I could operate mine.
I have a fairly good knowledge of electronics, but always get some advice from here before applying any of my ideas to fairly expensive LGB units!!

 

[Round n Round]

A few month ago I was down in Sussex, I called into Gaugemaster and sort of asked the question you have asked.

I was interested in using their Toggle Switches they sell for operating LGB points.

I was going to make up a control panel with track diagram and use their switches.

The reply I got when I asked could I use one of their CDU units in the circuit, was ... it should work.

That was not a good enough reply for me when I was going to invest in 20 switches ... so I didn't.

So, sorry, I have no answer to your problem but I suggest caution when you speak to Gaugemaster.

No doubt they will be happy to sell you some more point motors if it does not work.

 

[Neil Robinson]

That circuit board appears to have almost two of everything so my guess is that one half of the circuit is a smoothed half wave rectifier for one polarity of the ac input and the other half for the other polarity, those capacitors are usually polarity sensitive.
The diagram below shows the voltage on a capacitor on the output of a half wave rectifier. The stored energy is proportionate to the area under the curve. When the point motor is operated the energy from both the supply and the capacitor will be available.

 

[Neil Robinson]

A few month ago I was down in Sussex, I called into Gaugemaster and sort of asked the question you have asked.

I was interested in using their Toggle Switches they sell for operating LGB points.

I was going to make up a control panel with track diagram and use their switches.

The reply I got when I asked could I use one of their CDU units in the circuit, was ... it should work.

That was not a good enough reply for me when I was going to invest in 20 switches ... so I didn't.

The principle behind LGB point switches, Gaugemaster's version or any source of components using the circuit below is identical. On this occasion therefore your concern was overly cautious.

 

[minimans]

Thanks Neil now I see it! I couldn't figure the diodes but I forgot we are looking at A/C at this point .......................

 

[Round n Round]

The principle behind LGB point switches, Gaugemaster's version or any source of components using the circuit below is identical. On this occasion therefore your concern was overly cautious.

Thanks Neil, I take your point (no pun intended)

But my point was that the advice I was given as to if a CDU would work was not really convincing.

I am a bit cautious when I'm going to layout £60+

When there is a chance that the money spent might just go up in smoke at the flick of a switch.

 

[nicebutdim]

Well initial bench tests working well, seems to give the point quite a good throw. I'm using 2.5mm cable to travel about 7m, so should (?) be ok for getting the power there. As I'm making a rudimentary radio control system I still have to make the switch that will be operated by a servo, so will give it a proper test later, here goes....