Fitting power caps

[Graham]

Can someone give me the ins and outs of fitting power caps to overcome points/dirty bits of track please.

 

[Zerogee]

I assume you mean for DCC, Graham? (Actually, I don't know if capacitors will work at all on DC, will they?)
What decoder(s) are you using?

Jon.

 

[Graham]

Yes dcc. I am using a basic LGB decoder (The one with 4 wire tails and pins) 55021 I think. I have a Tsunami 2 rigged in as well but for sound only.

 

[Zerogee]

OK, hopefully someone here will know the specifics of connecting to a 55021 - I've had some fitted to Massoth decoders, which is a relatively easy job on an XL or XLS but requires some soldering skills on an LS or L.

Someone on here (was it Stockers?) built some very cheap, simple versions using a single large cap, a diode and a resistor - they are good for just a couple of seconds, which may well be all you need to get over point frogs and dirty spots on the track.
The commercial units like the Massoth Powercaps (which will keep a loco and sound board alive for quite some time, in the order of 20-30 seconds) have three wires, one of which is a control feed that still allows the decoder to be programmed while the capacitors are connected - if you don't use this, then a switch must be installed to put the caps out of circuit while doing any programming.

Jon.

 

[PhilP]

On a 55021, you would have to wire them in, and fit the switch.. Not even sure you could wire in on this model?? - Could not find manual atm..

 

[Greg Elmassian]

I believe that if you add a diode and inductor in parallel, then then that assembly in series with one of the leads of the "cap bank" you can have your cake and eat it too. The inductor helps with programming and inital inrush spike.

Zimo had some information on one of their decoder sheets.

I have to fit one to the Bachmann (SoundTraxx) Thomas the train decoder myself, so I will watch with interest.

Greg

 

[Graham]

Starting with just the basics where in the circuit are the fitted, across the motor or track connections or someplace else?

 

[PhilP]

Starting with just the basics where in the circuit are the fitted, across the motor or track connections or someplace else?

'Someplace else'

Decoder + and Decoder -
There is a third wire, for 'Buffer Control'. - You would need to wire a manual switch into this for a 55021 decoder..

As I said, I am not able to get at my notes at the moment, but from memory, you would need to solder wires to the board on a 55021.

 

[Deleted member 4232]

Moved

 

[PhilP]

Which appears to be empty..

<edit>
Get it now..
There is a, not very obvious, link to a download, as opposed to a list of threads..
<edit>

But perhaps someone can have a search-through, and populate it with a few previous threads??

T'is very close to shut-eye time here.. In fact SW, and both cats, are already on the case..
G'night all!

 

[Graham]

We have this area on the forum known as Resources, DCC, DIY & Stay Alive Voltage Buffers, 55021 is the first item!

Cool but how do I download it...I just keep going in circles

 

[Deleted member 4232]

Moved

 

[Graham]

Thanks......sometimes things are just tooo obvious

 

[Graham]

Hi John what Watt rating would you suggest for the resistor in the diy version?

 

[Deleted member 4232]

Moved

 

[Graham]

Hi Graham, all my DIY versions use 0.25W 1% resistors, the first ones I made, used 5% tolerance resistors and the Central Station used to "trip out" frequently, after carefully measuring their resistance value, a 5% swing on Far Eastern sourced resistors was a gross understatement, swapped them out for 1% tolerance, problem went away, CS stopped tripping out.

What's the colour band for 1%?

 

[Deleted member 4232]

What's the colour band for 1%?

Brown 1%

Gold 5%

 

[Graham]

Thanks John
Have made and fitted one per the instructions and improves performance greatly. Could I stack two of these to give a bit more capacity?

 

[Deleted member 4232]

Moved

 

[Graham]

All I can say is for a total cost of a couple of pounds the result is great.