Does anybody have a schematic for these ? Interesting application that could be adapted for a boat load of other things if I knew what was inside. Trying to avoid buying one and doing “non-destructive” dissassembly and analysis.
What’s it do?
I made a friend 4 “bi-directional signal bridge controls.” They sense the train with an IR detector and LED and turn on red, yellow or green leds. A switch indicates which direction. Runs on 5v DC. 3 AA batteries would probably work it for a long time.
Do you have schematic that you could share?
Just a PC board layout. All the works is in the program for the chip.
Thanks. Too bad don’t have a photo of components so I could do some technical detective work. I started my career as an Missile Electronics Tech in US Navy and followed up after discharge in college and working for old TRW and Hughes Aircraft before they forced me into “counting beans” instead of chasing electrons.
Technical detective work from a photo won’t tell you what the program in the chip is doing. Ok, the chip in the middle is an Atmel ATTiny 2313. The square thing in upper right is a PNA4602M 38KHZ infrared detector. In the bottom right is a non-descript IR LED. The 3 pin thing left of the LED is a 1k trimpot used to adjust the intensity. Left of that are some dip switches to set the operation mode. The pads on the right are the - ends of the Red, Yellow, Green, Red, Yellow, Green LEDs. The chip resistors are 220Ohm. A chip capacitor hides between + and - above the chip. Here’s an early prototype:
(http://outsidetrains.com/mls/signalbridgeproto.jpg)
The 2313 blinks the LED at 38KHZ. The detector is very sensitive, so the LED hides in a brass tube otherwise it will always see the flashes. When the detector sees the flashes reflected back from the train, it signals the 2313. The 2313 then turns off the green and turns on the red. When the train has passed, the detector doesn’t see the reflected flashes, and the 2313 turns off the red an on the yellow for a while, then switches back to green. The dip switch sets the direction. It works one set of lights and holds the other red. I added the trim pot 'cause while the prototype works, it kept mistaking the ceiling for the train. The PNA4602M is really sensitive. It’s actually the chip a TV uses to detect the IR signal from the remote. The second set of dip switches sets the yellow hold time. The board lets me mount the detector and LED on the opposite side if its more convenient. Chuck will be mounting it above the train in his signal bridge.
Tom, that’s very cool. You could probably market that.