eblc1388
Active Member
Edited by eblc1388: I built it and it works, on 18F4455, 16F628A, 16F877, 12F675 but failed on a 16F88.
Edited 2nd time by eblc1388: User Someone Electro built a modified version of the schematic and using 13V as Vpp he can also program a 16F88, 16F876A and 18F4550.
Edited 3rd time by eblc1388: A programmer based on modified version of the schematic and using 9V+3V batteries built and tested
Hi everyone,
I found the following from the Microchip discussion forum. The original thread is here:
New LPT programmer
On first look the circuit is very interesting as it use very few components. I have modified the circuit a bit by adding two resistors. You may also use the 78L05 instead of the 7805 voltage regulator. In addition, I would also use two capacitors(not shown) for the voltage regulator as kind of good practice. If it does not work, you can remove them and try the original circuit.
I just wonder with the original circuit, PIC's MCLR pin voltage can never rise above the LED forward voltage drop of 2.0V, how it would work in this case. Not to mention the high current that would kill both the opto-couplers.
If you ever tried to build it, please post back to let us know of the result.
Edited 2nd time by eblc1388: User Someone Electro built a modified version of the schematic and using 13V as Vpp he can also program a 16F88, 16F876A and 18F4550.
Edited 3rd time by eblc1388: A programmer based on modified version of the schematic and using 9V+3V batteries built and tested
Hi everyone,
I found the following from the Microchip discussion forum. The original thread is here:
New LPT programmer
On first look the circuit is very interesting as it use very few components. I have modified the circuit a bit by adding two resistors. You may also use the 78L05 instead of the 7805 voltage regulator. In addition, I would also use two capacitors(not shown) for the voltage regulator as kind of good practice. If it does not work, you can remove them and try the original circuit.
I just wonder with the original circuit, PIC's MCLR pin voltage can never rise above the LED forward voltage drop of 2.0V, how it would work in this case. Not to mention the high current that would kill both the opto-couplers.
If you ever tried to build it, please post back to let us know of the result.