To Control speed DC motor easily with a few parts in circuit.
The surge protection circuit important! Sometimes, our electrical appliances may damage easily by little high voltage surges. We can protect this problem.
This is the Transistor tester circuit into PCB. When your project do not works, the tester electronic parts or component be what need very much.
Here is the tone generator circuit,it is small size. I use IC digital CMOS 4011 quad NAND gate.