Re: How to measure distance?
Yeah, RADAR is a good choice, but again it is very difficult to build by hand because the component is overmuch and presision... I dont think that you can make radar just by using a panfry or a wok.
Back to IR. I'm sorry i cant give you any schematic. Anyway, basically it only consist of ir transmitter and a photo cell. Here's a hint:
1. Use photocell because the output is in mV and very sensitive.
2. Or use OPT101 from Texas Instrument, it got a built in instrument amplifier.
3. Use focusing lens (u can get it from a loop) to focus the light. If its hard to do, just use the sensor by itself.
4. Go to
www.maxim-ic.com to look for a bandpass filter IC. Order a free sample. refer to the data sheet for usage.
5. Detect the amplitude of the filtered signal. That would be the signal strength.
6. if you can, convert the signal to DC and convert the analog signal to digital.
7. Dont forget to blink the light source.
To be sure of the effect, try it first indoor.
Dont use any signal conditioner component and dont blink the LED.
Make sure the room is dark (dont have to be total). Dont turn on the LED just yet. Connect the photocell output to a voltmeter (digital will be helpful). The A to + and K (the shorter pin) to Com. You will see the actual voltage from the sensor. The voltage indicates the ambient light = Voffset. Now turn on the LED and move back and forth. U'll see the changes... the further u are from the led the closer the the Voltage to Voffset.
After you achieve this, i'm sure you know the rest. Contact me if you still confuse.