Post by thread:basic stamp infrared

Dear All, I am working on a Basic Stamp project that detects IR from a standard tv remote control. I tried to use a standard IR phototransistor but found that I had to place the remote control within 1/4" for it to work. I then tried using a transistor to amplify the circuit. I coupled the collectors of the phototransistor and transistor, and connected the emitter of the phototransistor to the base of the transistor. In a darkened room, the circuit worked great. But in normal room light, the circuit acted as if it was continuously detecting IR. I tried using an IR filter lens from a remote control to shield the phototransistor, but it did not seem to help. Question: How do I reduce the sensitivity of the IR phototransistor to normal light? Should I scrap this idea, and use the GP1U52X IR receiver module mentioned in Basic Stamp application note #11? Any help you can give me would be greatly appreciated! Mike Brothers spam_OUTelectronTakeThisOuTwln.com

Mike Brothers <.....electronKILLspam@spam@WLN.COM> wrote: >I am working on a Basic Stamp project that detects IR from a >standard tv remote control. I tried to use a standard IR >phototransistor but found that I had to place the remote control >within 1/4" for it to work. > .... >Question: How do I reduce the sensitivity of the IR phototransistor >to normal light? Should I scrap this idea, and use the GP1U52X IR >receiver module[?] Mike: IR remote controls modulate their signal on a 40 KHz (or so) carrier. Your receiver must include a highpass filter to block frequencies below this. The receiver modules are probably your best bet; they include the filter, amplifiers, etc. -Andy -- Andrew Warren - fastfwdKILLspamix.netcom.com Fast Forward Engineering, Vista, California

Mike wrote: >> I am working on a Basic Stamp project that detects IR from a >> standard tv remote control. I tried to use a standard IR >> phototransistor but found that I had to place the remote control >> within 1/4" for it to work. .... Why not using a special IR-receiver device like SH205(?)? Thease things work quite good (very sensitive) and aren't expensive. Inside there is an optical IR-filter, a 44kHz filter, impulseformer etc. They are supplied over a 100 Ohm resistor and need an electrolytic cap. At the out-pin delivers a recangular signal like that: IR _____|_|_|_|_______ _____ OUT ____| |_______ _____ | _ | 100R | |_| | |_____| +5V __/\/\___| | |____ out | | -||- + 10u There are some devices on the market, from different companies, sometimes optimized for different IR burst frequencies. Really great stuff! Lothar

> > I am working on a Basic Stamp project that detects IR from a > standard tv remote control. .....Should I scrap this idea, and use > the GP1U52X IR receiver? > Mike Brothers > .....electronKILLspam.....wln.com Hi Mike, I did this for an IBM PC on a parallel port. It was a NE555 -based transmitter and a GP1U52X receiver. The receiver was trivial using the module. The bitstream from TV/VCR remotes comes in at a very low rate but getting enough resolution from the PC clock is a challenge. I'd go for the GP1U52X approach. It's easy to use, widely available, and inexpensive. Ben