eptheta

Sorry, but what is R1 here ? a resistor of 1 Megaohm ?

Alright i may seem like an idiot here (since i am relatively new to electronics) but I'll try and explain "exactly" what i did: -my photodiode (like any LED) has a long end and a short end. I connected the long end to +5V and the short end to the base of the NPN transistor. -emitter to 0V -the load, which is the clock signal, was connected to the NOT gate on the 7404 and then to the clock input of my 4206. This setup worked for me and i kept it running for about 10 mins just to be sure, and it didn't blow up. I know i am probably wrong about this explanation so i'll put up a picture of what I've done(and a representation on paint), if that will help. So here's a complete representation of my circuit, ignoring the 4026 and 7 seg pins and connections: Also, my 7404 has 5 spare inverters. NOTE: i cant see the images so here are the links anyway: http://img685.imageshack.us/i/circcccopy.jpg/ http://img685.imageshack.us/i/circcc322.jpg/

Hi, Sorry, i did mean 0V not -5 V The diode is the right way round, and its not over heating. I'm using the Photo diode as a light dependent resistance not as a voltage source ( though it does both ) so it merely gives +V to the base allowing the transistor to work like a switch. My not gate is in TTL chip (7404) so it has a default high value, so i don't think i need a pull up resistor. My main problem is still the bouncing. Anything else i can do ?

I have created a circuit which is supposed to detect light from a laser (using a photodiode) and increment a counter every time the light is blocked. It works partially, but sometimes the signal bounces and the counter jumps from 1 to say 4 and then to 5 then 7 etc... it's just unstable. If i flash the laser on and off very slowly, then it registers the count more or less properly, but i want it to detect fast changes, for example me waving my hand back and forth in front of the laser. Here's a link to the diagram of my circuit. The counter circuit works perfectly, so there's no need to include it. http://img96.imageshack.us/img96/8761/circ.png If you can't improve or point out the faults in my design, could you perhaps suggest an appropriate alternative circuit that would suit my purpose ? If anyone here can help me i would be very grateful. Thanks