A good photodiode should have fast response, large surface are, small capacitance
and of course low cost. I’ve been looking for a good photodiode here in Philippines and BPW34 is the best thing around. It is available in two versions, a visible light version which is packaged into a water clear casing (BPW34) and an infrared version which has a visible light cutoff filter (BPW34F). It features a 7.5 square millimeter sensitive area, responsivity of 0.62 A/W @ 850nm. The really nice thing is that it costs only about 80 pesos. Photodiodes with large surface area as this one are commonly found in lightwave communications receivers (FSO) and photoelectric smoke detectors.

If you are using the classic parallel pic programmer using 7406 or 7407 buffer, you might have noticed that this PIC programmer design is a hit and miss device. Most of the time it would program the 16F84 devices but it could give you mixed results when you are programming the 16F877′s and 18F4220′s. If you run EPICWIN with this programmer under
PCs with more than 1 Ghz of cpu speed, you are going to encounter all sorts of error like “code verify error”, “code programming error”, etc.. But if you run it on machines with CPUs running at 800 Mhz or lower, the programmer seems to work fine.

This is a homemade DS89C420  programmer that was built by Glenjoy ( global moderator of electronicslab philipppines forum ). The programmer uses the MAX233
RS232 interface to eliminate those external capacitors required by MAX232. Although a bit
expensive, it is advisable to use zero insertion force sockets on the
programmer to maximize the life of the IC pins. For schematics and pcb layout, check out this link http://www.electronicslab.ph/forum/index.php?topic=84.0