Post by thread:[EE]: Diode question on the "El Cheapo" programmer

Hello, I am building the "El Cheapo" programmer according to Myke Predko's design as specified in his book Programming and Customizing the PIC Microcontroller. The design specifies the use of 1N914 diodes. It says that "Any Small Signal Silicon Diode can be used for this application". I bought diodes labeled "Silicon Zener Diodes, 30V, 1W, 5% Tol", part 1N4751AT. My question: are these parts compatible for this application? Voltages stay beneath 15V at all times. Thanks for your help, -Mike -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

In a word "yes", those diodes will work. Zener diodes have an added feature that they "breakdown" repeatably at precisly 30V, and they are usually used at the edge of such breakdown. Below their 30V Zener voltage they behave as ordinary diodes. Sherpa Doug > {Original Message removed}

It might well work because you stay below the zener (breakdown) voltage of the diodes, but it is not very neat. Why not use much cheaper stuff like the common 1N4148? Wouter {Original Message removed}

Hi Mike, Same comment as Wouter - while the Zener should work, I'd encourage you to use the specified 1N914 or 1N4148 diodes (small signal diodes you can buy at "Radio Shack"). As for the diodes you've bought, I'm surprised that they would fit in the holes of the PCB - 1 Watt Diodes are a lot larger than the 1N4148/1N914. myke {Original Message removed}