L298 4A H-bridge

[olof102]

Hi,
I'm about to build this **broken link removed**

It says that C1 and C2 should be 10nF decoupling caps. Will it work with ceramic capacitors?

And which transistors should I use as Q1 and Q2?

Also which diods should I use?

Sorry for my nooby questions. I would REALLY appreciate if somebody could help me out here!

 

[Gary B]

I see no problem using ceramics for decoupling high frequencies. Since I do not expect you to be sending control signals to this thing that measure in the low microsecond range, any cheap small signal NPN transistor should do, even the venerable 2N2222.

As far as diodes go, I have always been partial to the 1N400x family. They are cheap and rated at 1 amp. If I recall correctly, the 1N4004 has a PIV of 400 or 500 volts. They used to be available at Radio Shack for something like a dime a piece.

 

[olof102]

Hi again,
The motor draws around 2 amp constantly. Will the mentioned diods works? What does the diodes in the circuit do? Stop current to flow back in the IC?

 

[mneary]

Yes, 1N400x of any flavor will work as the diode. Yes, it keeps unwanted current out of the L298.
Any small signal NPN transistor will work, 2N2222 as mentioned, or 2N3904, BC546 thru BC550.