Circuit Project Electronic

This is circuit 300W Inverter power,so input battery 24V to Output 220Vac 50Hz 300W.
I used main Component IC CD4027 , NE555,CA3130 and LM7805. The transistor power MJ15003 driver transformer 24V 10A min. View Circuit
The VR1 - 100K is control Frequency output at 50Hz 50Hz or 60Hz at Square wave signal.
The VR2 - 50K [...]

Normally, in a digital voltmeter, high input impedance of the preamplifier stage is protected against very high voltages by two diodes. One of them is connected to the positive terminal and the other one is connected to the negative terminal of the power supply. Practically this kind of protection is very sufficient. But the diodes [...]

Introduction
With this mAh meter you can check the mAh capacitance of your NiCad or NiMH rechargeable batteries
Normally the cheaper NiCad AA-type cells have a capacitance of 500-750mAh (NiCAD) the more expensive
NiMH AA-cells types are up to 1800mAh.
I built this circuit because the capacitance of some of my older NiCad batteries seemed to be quite [...]