Repurposing an old IR remote

[DrG]

BLUF: Just a little hobby project for S&G.

I was going through this thread - https://www.eevblog.com/forum/chat/making-a-simple-ir-transmitter/msg3299420/#msg3299420 - where I said "I didn't have a need for a great distance, but if I did, I would go toward cannibalizing one of the many old remotes still hanging around long after their devices have gone away.". That got me thinking about doing just that and this is what I came up with.

Here is the remote. I think it was from an old VCR (Yes, kids, many of us had VCRs).



This is why you take the batteries out of things before you toss them in a box.



Looking into it a bit, there is not much apart from the keyboard. No doubt, this is the brain.



I looked around a bit for info on the chip, but not too hard because although I am sure it runs the keyboard and the IR transmitter, I am not really interested in figuring out how to use that chip. I just want a general purpose IR transmitter.

Here you see the small number of additional components. A 455 kHz ceramic resonator, with its two caps, a 2.2 ohm current-limiting resistor, a C2120Y NPN transistor (datasheet available), and a power supply cap.



That's it, except for the two IR LEDS on the front end with a lens....that's the part I wanted for sure...and since the transistor and current-limiting resistor are there for the taking, maybe I can combine everything on a small board.



On the left is what I think is the schematic (minus the BU3738F stuff) and on the right is the schematic for the circuit I want. Note that I have it set up so that I can easily add to the current-limiting resistor. I measured the draw of the original circuit at neat ~240 mA at 3.0V and I might not want it that "strong", especially if I want to use it at 3.3V or 5V and with a PS that might not be able to supply that much current. But, I could use it as is if I wanted maximum distance capability.



Out comes the Dremel with the saw attachment (I love that thing) and after a little coercion, de-soldering, re-soldering and a bit of cursing, I get this.



Slap the top on and it is breadboard friendly.



Did some testing and everything works as it should, Clean up, make a file with some notes, and it goes in the parts drawer.

That's all I got