From: Self To: bascom@grote.net Subject: Re: [bascom] nz source for SFH506-36 Send reply to: adean@adx.co.nz Date sent: Tue, 22 Aug 2000 23:27:43 > Does anyone know of a source for this part in NZ for a one off please That may be a little off topic for this list, but I can tell y'all something about these devices (having designed a commercial product using an IR receiver module - uses BASCOM-LT actually). IR receiver modules are basically interchangeable if you use a standard IR protocol (such as RC5) and aren't asking maximum distance from them. They are tuned to a particular frequency (eg SFH506-36 is "36kHz") but this is often broad enough that they work ok on different bands up close. 38kHz is most common. They have 3 pins: +5V (or 3V very rare), GND and data out (open collector lightly pulled high). Basically, the output goes low when they receive IR pulsing on/off at the tuning frequency. There is a ton of other processing which can get very complex and do unexpected things to your signal, so if you're doing anything nonstandard read the datasheet (which is often next to useless for this purpose) and any application notes you can find explaining how they do their reception (AGC, variable thresholds, noise filtering). Vishay have a good one. In the end I chose the Vishay TSOP17xx and 11xx series for transmitting raw RS232 (actually, receiving modulated RS232, but receiver choice totally defines what you can transmit and how fast). The SFH506 looks like it may operate similar to the Vishay parts (I got a Vishay TSOP1738 from South Island Components, Christchurch, New Zealand, they have a website order thing too. Very lucky they had some.). Most asian brands (Sharp, Liteon, Kondenshi, JRC...) use simpler signal processing and while still fine for RC5, faster RS232 will give big problems, and you may end up in a panic trying to explain this to your clients, for example... Some pointers if you want to transmit RS232: - Make it so the IR LED pulses on the (active) low UART output. A 555 oscillator is usually fine for the modulation. - Be very wary of moving bit transitions in received RS232 data with changing reception distance, length into your packet, data content etc. You may have to run it a lot slower than it first appears. As a general purpose receiver the Vishay TSOP11xx series is excellent in this respect (ie it doesn't do it much) and well specified (in fact specified at all!). - You will have limit your maximum RS232 "duty cycle" (%age of time UART signal is low for over about one second) to probably under 50%. More than this and the receiver thinks the modulation is continuous noise, so backs off its gain until the "noise" disappears. Hope this helps someone, and sorry I couldn't recommend a NZ source for a Siemens/Infineon part, Antony.