This PWM generator also works as servotester, it supports all kinds of servos, which dont need more then 5V
Operating voltage: 5V
Max PWM current: 1 A
PWM frequency (by now) : 500HZ , I am trying to make that changeable, if you know how, let me know :)
small prize ;)
So lets get started!
Step 1: Material and Tools
2 Resistors (450 OHM)
1 Resistor (1 kOHM)
1 BC548 NPN Transistor (or equal)
1 BC516 PNP Transistor (or equal)
1 Potentiometer (10 kOHM or higher)
serval kinds of terminals (picture 1)
some unisolated wire
1 eight pin IC holder
1 Attiny (25/45/85) I used the Attiny45
a cutter knife
a attiny programmer (Arduino Uno)
Step 2: PCB layout
The PWM output will be on pin 2 of the Attiny and the analog input will be on pin 4. The BC558 is used as Inverter and as a first amplifier.
After that the BC516 is used to get the current to a maximum rating of 1A, what is actual very good and can drive a pc fan or a dc Motor!!!!
note: the PWM signal is only against 0V not against 5V!
!!! take care dont wire the Transistors wrong, it can cause a shortcircuit!!!