Designed and worked first time.

[Harry Bloomfield, Esq.]

Nothing much really, just a simple booster to supply a bright LED - but I've not needed to design anything for years.....

My garage's roller shutter has a 24volt dc IR beam across the door, which would only allow the door to be closed and lot an LED at the far end, when the door was clear and my car in just far enough.

The unit got soaked with rain a few weeks ago and it died on me. I had been able to hack into it originally, to power the remote LED.

I had a spare IR unit on the shelf, different make and there was no way to hack into it for the LED. The signal back from the unit to enable the door to close, was high-ish impedance, 13volt DC, not able to drive an LED, so time to coble a one transistor amp together to boost it to drive the LED.

I mostly just repair what goes faulty these days, so I had to get the reference books out for transistor types and specs, based on what I had in the drawer. I ended up with a 2SC945.

[newshound]

Don't think I have ever built anything that worked first time :-)

[Brian Gaff (Sofa]

I used to make a lot of voltage regulating little modules for running stuff from non standard psus or car batteries when I was young, and they all worked first time. Hardly rocket science of course, but then some bright spark invented the LM317 which did the whole thing including fold back protection in the one device and all I needed was a couple of capacitors and a pre set pot.

Brian