Equipped with a PIC16F676 this module drives any kind of DC device (capacitive or inductive; from 10-60V) with optical isolation. The PIC is intended to be used with the internal oscillator. Furthermore 5 I/O-pins are brought out on extra PIN-headers: RA0, RA1, RA2, RA4 and RA5 ( AD/interrupt/counter/comparator-peripherals). They are available for the user to implement many kind of control/sensor-applications as well as frequency counting-devices (eg flow meter-measurements). With the onboard ICSP-connector you can program the PIC directly according to your needs.

The board is not limited to the IRF540N (designed to pass the max current at gate voltages of around 10 Volts) - of course you can use any other suitable MOSFET (eg logic level types like IRLZ44N). If the MOSFET does not turn off replace R4/7/10/13/16/19 with 10K (instead of 1K).

The optocoupler used here is an PC817, which is quite slow and usually used in on/off-switches. You can replace it with any other type more suitable for your application.

Important: depending on the used regulator (LM2575 [1A max] or LM2576 [3A max]) and the application the inductor chosen must be rated for operation at the LM2575 switching frequency (52kHz) and for a current rating of 1.15 × I LOAD (check the data sheet for choosing the right inductor). For the LM2575 you will need the 1N5819 and for the LM2576 the 1N5822 diode. If you want to power the board directly from a stabilized 5V-power supply then remove jumper JP5 and connect the power supply directly to headers JP3 (GND) and JP4(+5V).

Recommendation: do not attach anything except for the programmer to ICSP-DAT (PGD) and ICSP-CLK (PGC) when you program the PIC!

V1.5: the LM2575 was turned 180° to fit better on the board and to keep more distance to the inductor.

V1.6: another mounting hole was added for better stability and some components were slightly moved for better positioning. For those who like to attach eg the PICkit3 directly to the ICSP-terminal, the ICSP-terminal-pins were turned around so that the PICkit3 is showing the upper side to the user now.

If the RESET button does not work as desired then remove the 1N4148 diode (D3) from MCLR-RESET circuitry and bridge with a wire.

Do not leave any unused pins floating - make them outputs and drive them to logical 0.

Please consider e.g. the PIC16F18426 if you need more program flash memory and communication peripherals.

The board was tested and it is working correctly.

PS: I added also the new version with the more powerful PIC16F18446 V1.2 - the PCB is optimized and several I/O-pins are brought out in terminals.