Author Topic: 1:1 FRED 12v flash circuit  (Read 487 times)

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VonRyan

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1:1 FRED 12v flash circuit
« on: January 12, 2018, 09:32:20 PM »
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I'm helping a friend get a 1:1 FRED working again. The original electronics are 100% dead, so time to build new!

My friend has located a direct LED replacement for the GE 94 bulb his FRED used, and his FRED originally had a flash rate of 40 flashes per minute.

So I gotta come up with a 12v flashing circuit to recreate the original flash of the FRED, the idea being to use a couple cheap/plentiful 6v lantern batteries as the power source.

Google didn't give me what I wanted, so I've come out of hibernation once again to ask for your help with this.
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peteski

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Re: 1:1 FRED 12v flash circuit
« Reply #1 on: January 12, 2018, 10:54:18 PM »
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A 555 timer chip is one of the easiest and simplest ways to build a flasher (other than using discrete transistor multi-vibrator).  But that will not simulate the gradual fade out of the light of the original 1:1 FRED.

Why not try to repair the original electronics?  Is is a complicated circuit?  Is it really truly 100% dead (not just one or 2 components)?  All fried?  :|
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VonRyan

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Re: 1:1 FRED 12v flash circuit
« Reply #2 on: January 13, 2018, 09:24:58 AM »
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A 555 timer chip is one of the easiest and simplest ways to build a flasher (other than using discrete transistor multi-vibrator).  But that will not simulate the gradual fade out of the light of the original 1:1 FRED.

Why not try to repair the original electronics?  Is is a complicated circuit?  Is it really truly 100% dead (not just one or 2 components)?  All fried?  :|

The original components were a resin encased block, and apparently half of it is missing anyhow, so a new circuit is required.

Ideally a fade in/out similar to the original would be sweet, but just a consistent steady blink at the same 40 per minute rate as the original could be fine and dandy as well.
Cody W Fisher - Modeler of the PRR, PRSL, GWR, SZD, and DRG

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peteski

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Re: 1:1 FRED 12v flash circuit
« Reply #3 on: January 13, 2018, 04:07:46 PM »
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Ah, that makes sense: a weatherproof electronic module. Not serviceable.

What are the specs of the LED bulb?  Voltage and current that is.  I know you want to use a 6V lantern battery.

Also do you happen to know  what was the duration of the on bulb's "on" state?  I know that it wasn't a very quick (strobe-like) flash, but it wasn't a an even on/off cycle either.
« Last Edit: January 13, 2018, 04:14:49 PM by peteski »
--- Peteski de Snarkski

-"Look at me, I'm satirical!!!"
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