multi direction dc motor

[sherjan]

[dear i are you using microcontroller and a DC motor than there is no need of using four transistors. ti rotate the motor in two direction, you can use two transister and by inverting pins of microcontroller.

 

[BobK]

sherjan,

Only if you have dual supplies. A 4 transistor H-bridge does this with a single supply.

Bob

 

[Resqueline]

You're right about the BD681G greeniekin, it's a Darlington transistor. They have fantastic gain figures but suffer from very high saturation voltages.
As you also found the 2N2222 has a quite high Vsat too at its higher current ranges and is thus not suitable for this low-voltage application.
But so-called lo-sat transistors are plentiful, just Google for the term and you'll get half a million references to browse through, also from suppliers.
I remember being astonished by the extraordinary spec's of the Zetex transistor range some 20 years ago, but there are other good makes too.
Attached is a suggestion for a MOSFET bridge driver circuit. Again I have no specific transistor reference since there are so many to choose from.
It's not tried and tested but it should work. The NPN can be a logic-level N-channel instead. Also here take care not to take both inputs high at the same time.

 

[greeniekin]

Well I really didn't find any better parts, and in some ways I feel stupid.
I was using an arduino uno. Which has a 5v regulator inside it and I was trying to use that to power my h-bridge. I ended up directly hooking it up to the 9v battery that powered the arduino. I didn't think of this initially because i was plugging an adapter directly into it. I probably could have hooked the positive lead from my h-bridge int the Vin connection on the arduino and it would still work when the arduino is plugged into the wall adapter. I have not tried it though.

In the future I might just use a motor driver chip, but it was a great learning experience.

though Resqueline I will look into that as I would like to use some smaller and lighter batteries in the future.

 

[jackorocko]

http://www.adafruit.com/products/81

Or just buy a L293D

 

[Resqueline]

If you searched only Jaycar I'm not surprised you didn't find any good transistors. Their selection leaves something to be desired.
I spent some time searching DigiKey and compiled this list of small (TO92) high-gain low-sat transistors. It's by no means complete.

2SB1592(0RA), PNP, -25V, -3A, 220mV @ 25mA & 1.4A, 130 @ 1.4A & 2V, 1W, 150MHz, TO-226-3, TO-92NL-A1 Long Body.

FPN530A, NPN, 30V, 3A, 250mV @ 100mA & 1A, 250 @ 100mA & 2V, 1W, 150MHz, TO-226-3, TO-92-3 Long Body.
FPN630A, PNP, -30V, -3A, 250mV @ 100mA & 1A, 250 @ 100mA & 2V, 1W, 100MHz, TO-226-3, TO-92-3 Long Body.

ZTX1051A, NPN, 40V, 4A, 210mV @ 100mA & 4A, 300 @ 1A & 2V, 1W, 155MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX869, NPN, 25V, 5A, 220mV @ 100mA & 5A, 300 @ 1A & 1V, 1.2W, 100MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX849, NPN, 30V, 5A, 220mV @ 200mA & 5A, 100 @ 1A & 1V, 1.2W, 100MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX1049A, NPN, 25V, 4A, 220mV @ 50mA & 4A, 300 @ 1A & 2V, 1W, 180MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX618, NPN, 20V, 3.5A, 255mV @ 50mA & 3.5A, 300 @ 200mA & 2V, 1W, 140MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX718, PNP, -20V, -2.5A, 260mV @ 200mA & 2.5A, 150 @ 2A & 2V, 1W, 180MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX1149A, PNP, -25V, -3A, 300mV @ 70mA & 3A, 250 @ 500mA & 2V, 1W, 135MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX948, PNP, -20V, -4.5A, 310mV @ 300mA & 5A, 100 @ 1A & 1V, 1.2W, 80MHz, TO-226-3 (TO-226AA), TO-92-3

ZTX949, PNP, -30V, -4.5A, 320mV @ 300mA & 5A, 100 @ 1A & 1V, 1.58W, 100MHz, TO-226-3 (TO-226AA), TO-92-3

STX690A, NPN, 30V, 3A, 400mV @ 100mA & 3A, 100 @ 500mA & 2V, 900mW, 100MHz, TO-226-3 (TO-226AA), TO-92-3