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Author Topic: Status LED  (Read 165 times)

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Offline sparrowhawk

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Status LED
« on: November 18, 2019, 06:33:55 PM »
I have a brake control unit which controls entry to a terminal station . The dcc
supply just one leg is just routed through a switch to control its operation .
Can I use a led to show status although the supply A.C and if so how to I wire
it up ?

Offline ntpntpntp

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Re: Status LED
« Reply #1 on: November 18, 2019, 06:49:02 PM »
It would help if you tell us what module it is exactly?  Is it some sort of "brake on DC" module?
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline sparrowhawk

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Re: Status LED
« Reply #2 on: November 19, 2019, 03:49:31 PM »
it is a standard lenz brake module BM1 the right hand rail supply is routed through it so the loco automatically brakes . To overcome the auto braking you can bypass the brake module via a switch it is this that I would like to link to a led to indicate
its status ie ON or OFF

Offline class37025

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Re: Status LED
« Reply #3 on: November 19, 2019, 04:08:12 PM »
I'd think a D/P-D/T on/off switch would be easiest, one side cut into the feed to the unit, the other with an input  feed for the LED, the other side feeding to the LED.

switch in on position would feed power to unit and LED, switch in off position feeds to both broken, so LED off.
typed by fur box mechanic - dictated by brain on a chain

Offline ntpntpntp

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Re: Status LED
« Reply #4 on: November 19, 2019, 06:23:49 PM »
You can certainly use an LED with a suitable resistor - say 1.5k ohms if it's being powered from the DCC supply at around 15V?

With in AC supply it's usually recommended to fit an ordinary signal diode in inverse-parallel with the LED to protect the latter from the reverse voltage, but to be honest I've never bothered with that diode and I've not had any failures with my LEDs on AC at those sort of voltages.

Alternatively use a double pole switch as @class37025  suggests, and power the LED with DC - still with a suitable resistor of course  :)
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline Nigel Cliffe

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Re: Status LED
« Reply #5 on: November 19, 2019, 09:22:33 PM »
You can certainly use an LED with a suitable resistor - say 1.5k ohms if it's being powered from the DCC supply at around 15V?

With in AC supply it's usually recommended to fit an ordinary signal diode in inverse-parallel with the LED to protect the latter from the reverse voltage, but to be honest I've never bothered with that diode …

Or use two LEDs, back to back (ie. Anode to Cathode) with a shared resistor.  Thus, one LED lights on each half of the DCC signal, and in doing so, protects the other LED from an excessively high reverse voltage. 


- Nigel

 

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