Loksound 5 decoder and stay alive

[Roger Sunderland]

Hello, I have a question. I wish to fit a new loksound 5 micro decoder, 8 pin, to a Hornby J50. Pickup is not that reliable and I'd prefer to fit a "stay alive" to it as well. However I'm not going to pay £30 + for an ESU power pack. I've had a lot of success with the Zimo stay alives . Question is can I fit one to an ESU Loksound micro with impunity?

[BWsTrains]

On 05/08/2019 at 04:06, Roger Sunderland said:

Hello, I have a question. I wish to fit a new loksound 5 micro decoder, 8 pin, to a Hornby J50. Pickup is not that reliable and I'd prefer to fit a "stay alive" to it as well. However I'm not going to pay £30 + for an ESU power pack. I've had a lot of success with the Zimo stay alives . Question is can I fit one to an ESU Loksound micro with impunity?

I've read somewhere that Loksound chips support only their proprietary stay alive so fitting another is not on, voids warranty may wreck chip. Will try to find link and attach as edit.

 

http://www.dccguy.com/?s=loksound

 

see final 2 paragraphs with feedback from Loksound - the info I was remembering.

 

Colin

 

 

Edited August 6, 2019 by BWsTrains
addition

[55020]

I've had no issues fitting some non-ESU stay alive units to Loksound decoders, so my experience echos that of Richard above.  

 

The quote on the DCCguy website doesn't state it will invalidate the warranty, but specifically says "in the future the company may have to disallow warranty replacements for decoders damaged in this way".  I cannot find anything on the ESU website to indicate they have implemented any change to the generous warranty they have in place.  In fact the opposite exists, in that the Loksound manuals (incl. the Loksound 5) still show how to fit a non-ESU stay alive unit.  

 

It will be interesting to see if anyone can provide a first hand experience of a decoder being damaged by a stay alive unit.

 

There's some great advice here:   http://www.sbs4dcc.com/tutorialstipstricks/esuloksoundv40andselectkeepalive.html

 

Also do check the decoder manual, available for download from the ESU website.

 

 

 

[RobjUK]

6 hours ago, BWsTrains said:

I've read somewhere that Loksound chips support only their proprietary stay alive so fitting another is not on, voids warranty may wreck chip. Will try to find link and attach as edit.

 

http://www.dccguy.com/?s=loksound

 

see final 2 paragraphs with feedback from Loksound - the info I was remembering.

 

 

ESU and some other decoders have a third connection for their own stay alive unit, which is a 5V level signal.

 

If that were accidentally cross-connected with the 12 .. 18V "U+" (as its labelled in that sbs4dcc link) rectified track voltage that a simple two-wire stay alive unit uses, the decoder would almost certainly be damaged, if not totally wrecked..

 

That's the part that would void the warranty.

 

As long as a DiY stay alive is only connected to the proper terminals it should work fine. Just allow for a switch or disconnect for programming and disable DC operating in the controller CV options.

 

I've added massive ones (6 x 10 farad in series) on some Lenz decoders that are supposed to have a proprietary three wire unit, they work perfectly.

 

[Hamburger]

Hi Richard,

how did you solve the problem that the SC68 is only good for up to 15 V which means roughly 16 V track voltage?

[Nigelcliffe]

I'd be wary of a SC68 without some sort of over-voltage protection.  The cruder DIY method is a 16v (or 15v) Zener diode over the SC68, if the applied voltage exceeds 16v, the Zener conducts, the charging resistor limits the max current taken by the Zener.   
The method I use whenever I have space, and a decoder without a 16v stay-alive circuit, is a Zimo SACC16 module; that has charging, voltage regulation, etc.. all in a small PCB. 

[Roger Sunderland]

Thanks all that's interesting. I've used Zimo SC68s together with their SACC16 boards on many models - but with Zimo decoders . Nigel, if I interpret correctly it would be fine to do the same with an ESU micro, without the need for resistors/diodes?

[Nigelcliffe]

1 hour ago, Richard Croft said:

I use a diode and resistor on the positive wire to the super capacitor, is this what you mean? the resistor slows down the flow into the capacitor and the diode allows full flow out. Thats my understanding of it based on what I was told by one of the big digital suppliers.

 

Richard

 

No, not those two components. 

The diode+resistor you are using ONLY limits the incoming current, stopping the capacitor from overloading either the decoder or the DCC system when charging from empty.   It provides no voltage regulation. 

If you exceed the voltage rating of the capacitor, then it can fail (and some fail with a fairly big bang).   So, standard rule of thumb is to have a decent head-room, and use 25v (or higher) rated capacitors.  Or, have some circuitry to protect things.  Or risk a bang.

 

 

There are many ways to limit the voltage over the capacitors, the simplest/crudest is to place a Zener Diode rated at 15v or 16v (a device which conducts when the Zener voltage is reached) in parallel with the capacitors.  Exceed the Zener voltage, and the Zener conducts, providing a voltage limit.   Zener diodes are tiny.

 

Carsten Berger covers it (the diagrams are readable even if German isn't)

https://www.1001-digital.de/pages/basteln-bauen/elektronisches/anleitungen/pufferschaltung-fuer-16-v-smd-kondensatoren.php

 

 

The Zimo SACC16 does a better job for about £10.

 

 

 

46 minutes ago, Roger Sunderland said:

Thanks all that's interesting. I've used Zimo SC68s together with their SACC16 boards on many models - but with Zimo decoders . Nigel, if I interpret correctly it would be fine to do the same with an ESU micro, without the need for resistors/diodes?

 

Correct, the SACC16 does a better job of things, providing voltage regulation as well as a charging/discharging circuit.   This assumes the ESU Micro V5 is similar to the V4, which appears to be the case from the manuals - I've not had cause to install a V5 yet.    I also agree with Richard's earlier comment in the thread about using the loco-side of a NEXT socket, rather than fixing wires to a decoder, unless there is an overwhelming space constraint - the NEXT socket has pins defined for decoder positive and negative, and hence stay-alive circuits. 

 

Some Zimo decoders include the 16v regulation of the SACC16 on the decoder, so you don't need the SACC16 module, or any other regulation (resistors/diodes).   

 

- Nigel

[Roger Sunderland]

Thanks very much Nigel, helpful as always. Also Richard. I like the idea of using the next18 socket.

[RobjUK]

10 hours ago, Richard Croft said:

so I would literally put one of these between the positive and negative on the SC68 then use it as I have been

 

There must be a resistor between any power source and the zener, to limit the current in to it. 

 

Divide the power rating of the zener by its voltage to get the maximum possible current it can take.  Then try to limit the current to around half that, as it's likely to be somewhere with no air flow and it would rather hot at maximum current.

 

You can get zeners rated from 0.4W up to about 5W in wire ended types & you can use two or more lower voltage ones in series to share the power dissipation between them.

 

If you are using a typical DiY power pack with a resistor & diode combination to control charging, you can just connect across the capacitor(s) and that resistor limits the current anyway - but for a commercial unit you probably have to connect directly across the capacitor bank, for the zener current to be limited by whatever change limiting circuit that has.

 

 

[Hamburger]

In my eyes calculation should be as follows:

 

To be on the safe side, calculate max current first.

So, divide max possible track voltage by ohms of charging resistor, example 20 volts / 100 ohms = 0.2 amps.

(Resistance of capacitor and Zener is low, so I dont take it into account).

 

Multiply this with voltage drop on the Zener, example 15 volts * 0.2 amps = 3 watts.

 

Take into account that the resistor also has to withstand the load.

Voltage drop in this example is 5 V, so 0.2 A * 5 V = 1 W !!!

 

Can please anyone confirm this or correct my assumption if wrong?

Thanks

[Nigelcliffe]

2 hours ago, Hamburger said:

In my eyes calculation should be as follows:

 

To be on the safe side, calculate max current first.

So, divide max possible track voltage by ohms of charging resistor, example 20 volts / 100 ohms = 0.2 amps.

(Resistance of capacitor and Zener is low, so I dont take it into account).

 

At this point, you're assuming zero volts over the capacitors, so you're calculating the max current the resistor could handle if subjected to 20v at the track.   Or, you're protecting against 35v at the track.   Therefore, I think your estimates are four times to high...

 

- Nigel

  

[RobjUK]

3 hours ago, Hamburger said:

To be on the safe side, calculate max current first.

So, divide max possible track voltage by ohms of charging resistor, example 20 volts / 100 ohms = 0.2 amps.

(Resistance of capacitor and Zener is low, so I dont take it into account).

 

The zener is across the capacitor(s) so takes no current unless they reach the zener voltage - 15V or whatever.

 

The resistor needs to be able to handle the peak charging current, but with a small cap bank that will be very brief.

If it can handle the track voltage OK it's ratings are more than enough.

 

The zener current will be the difference between the zener voltage and track voltage (assuming the track voltage is greater), divided by the resistor value.

 

eg. With a 15V zener, 18V track and 100 Ohm resistor that's 3V across the resistor.

(Actually more like 2V due to the voltage drop in the decoder rectifiers, but that gives some safety margin).

 

3V / 100 Ohms = 30mA

30mA through a 15V zener = 0.03 x 15 = 0.45 watts

 

Too much for a 400mW one, so use a 1.2W or larger.

 

 

[Hamburger]

Thanks Nigel and Rob, youre right, the drop across the resistor is just 5 V so its just 0.05 A . . . 

means 0.75 W for the Zener and 0.25 W for the R.

[Graham Radish]

A 100 ohm resistor, 25v cap and a 1n20007 diode, you dont need an esu branded stayalive, but as i use traincontroller and want to have accurate running i only use a 25v 470ohm capacitor otherwise the train just keeps going when being told to stop, the capacitor only needs to be there to stop micro stutters really (1/4 second) this is enough to ensure good running

Edited September 6, 2020 by Graham Radish

[boxbrownie]

Raising this from the grave (although still relatively fresh) I have a Loksound V5 Micro 8 pin chip, I’d like to add a stay alive and I see from the ESU diagrams the decoder has pads on the board for Ground, Positive and 5v signal all in a row….the decoder I have looks like it already has flying wires attached to these pads as Orange(or Red?) to the U+ (positive) and  White wire to the Aux7 pad and a black wire to the Ground pad…….I am assuming I can use the Pos and Ground wires to connect a stay alive unit (with built in charge circuit)?

 

Anyone know if this is correct?

[boxbrownie]

13 hours ago, Richard Croft said:

you can yes, I regularly use Laisdcc stay alives which are small and effective with V5 micros, red from the decoder to blue (positive) on the stay alive and black to black, (ground)

 

Richard

Brilliant, thanks Richard…..I suspected as much but preferred to be on the safe side.

 

ps. The LAIS are my preferred stay alives.

Edited December 6, 2021 by boxbrownie