LaisDCC 860052 - Aux 3-4 Logic Level Function Amplifier Board

[Roy Langridge]

I have stumbled across this neat little board from LaisDCC: LaisDCC 860052.

 

I know their decoders get mixed reviews, but some of their interface boards are fantastic value. There are no instructions on the LaisDCC website and a UK vendor of the board says you connect track supply on one side with the logic outputs and your LEDs on the other. Now, I find that hard to believe as the board itself is marked DC and GND on the input side and that would not fit with a DCC supply being a form of AC.

 

I assume, therefore, that GND goes to pin 20 on a 21pin decoder, but what should be connected to the DC? I can see two choices, pin 16 (+ve) or pin 12 (VCC). Given Pin 12 is not mandatory and is at the decoder internal voltage,  I am assuming that I use Pin 16 which is the +ve side for normal functions. However, this seems a bit counter intuitive as surely the power is then being supplied from the function side of the chip rather than from a more direct power rectified from the track supply.

 

Anybody used one of these or able to confirm/refute my logic please?

 

Many thanks,

Roy

 

 

[markw]

I have not used the Lais version, but have built similar circuits myself.

You are correct

GND to pin 20

DC to pin 16 (blue)

 

See https://www.aliexpress.com/i/4000337871670.html

For a better description of the connections.

Edited February 25, 2021 by markw
extra space

[Roy Langridge]

On 25/02/2021 at 11:09, markw said:

I have not used the Lais version, but have built similar circuits myself.

You are correct

GND to pin 20

DC to pin 16 (blue)

 

See https://www.aliexpress.com/i/4000337871670.html

For a better description of the connections.

 

First one all wired up and working perfectly. Thanks for your help.

 

Roy

 

[NFWEM57]

A supplementary question.  Are the outputs a sink for a current, similar to the lights and Aux1/Aux2 or are they a voltage source for load which is connected to ground (GND).

[Crosland]

The spec is a bit lacking in information.

 

Why would you want an amplifier for LEDs?

[NFWEM57]

3 hours ago, Crosland said:

Why would you want an amplifier for LEDs?

Hi,

 

At present I use another external circuit to switch in direction sensitive lighting, For example I use F1 to select Aux 1 which provides via additional circuitry, separate power to the red running lights with the ground provide by white or yellow as usual. Similarity F2 selects Aux 2 which provides power to cab lights again with ground via white or yellow.  Switch off the lights and all lights go off.  So if the amplifier selected by the logic output can provide the voltage then I can dispense with the external circuit I currently use.  In summary I have:

• F0 - Head Code and White Running Lights On
• F1 - Red Running Lights On - Direction Sensitive and provided F0 selected.
• F2 - Cab Lights On - Direction Sensitive and provided F0 selected.  Will also function map to moving / non moving in future.

So, just 3 function buttons for all the light combinations.  Other solutions use a plethora of functions and aux connections.  So, a current/voltage source rather than a current sink is what I am after.

 

Hope this makes sense.

 

Patrick

Edited January 18, 2022 by NFWEM57

[NFWEM57]

Further Clarification and Additional Info

 

If you are using 8 pin DCC decoders there is usually no ground connection only power (blue) and Aux0 (lights), Aux1 and Aux 2 selectable current sinks.  What is required is to make Aux 1 and Aux 2 generate power (when selected) that can be used with Aux0 current sinks (white & yellow) to provide additional selectable direction sensitive lights such as independently switchable red and cab lights where selecting Aux 1 or 2 switch on the lights; but only if F0 is selected as well.  I have developed a small circuit that does just that, it would be even smaller with surface mount components, and had hoped the LaisDCC would be the solution but it is nothing more than a dual channel logic driven current sink.   So, looks like I will have to continue with my own design.  As I have a need for many dozens of these circuits for my locomotives, a bespoke surface mount PCB looks like being the answer.  Then again, i could pass the design to 'Stanley' at LaisDCC and they might manufacture such a product.

 

The design works well and I have sold on a few older locos thus modified.

[NFWEM57]

Not a single response..!