View Full Version : ARP - Cheap HBridge

05-19-2009, 01:07 AM

ARP is back on mind again and this time ill atleast get 100 kits made. I have somewhat decided on the base platform which is shown below -


Now the question , which HBridge or motor drivers do you think can drive the motors above in least cost possible ?

L293 could do the Job but is there are cheaper alternative , since we are getting the boards fabricated assembly is not an issue.

05-19-2009, 08:16 AM
BD139s and BD140s?
You can finish the whole thing in less than 30rs if you use them. There will also be a safe margin for overloading as BD139s support 1A max. collector current.

05-19-2009, 10:21 AM
The board looks really good and yes the transistor option could be a cheap alternative.

Good work Sir Vikas

05-19-2009, 10:29 AM
l293D... small and sweet.. though a bit expensive compared to making an h bridge with discrete components...it saves a lot of space... and easier to replace if it gets damaged

05-19-2009, 02:04 PM
Hi all,
transistors,i think is the best option.The other thing could be BD139 as suhasm said .They are cheap as far as L293 is concerned.

Reagrds Akshay,

05-21-2009, 04:36 AM
I agree with others on a discrete BJT based solution.
Its economical and sufficient.
Thats what you will find in most toy cars with such size motors and batteries.
just remember to use any fast recovery diodes || to your BJTs.

L293 is anyway not suitable if you are planning on a 3V battery system (as shown in photo) because its recommended operating range is 4.5V+.
(and for a mass produced design I think its better to stick with specs even if it "worked" below that).

05-21-2009, 02:08 PM
Is TC4427/4424 available in india?
An article on robotroom.com says that it is a 2 Amp Hbridge in 8 pin DIP package. I guess you could use that if its cheap.

05-21-2009, 04:49 PM
Hi all,
Heres the link http://www.robotroom.com/HBridge.html
The other option that suhasm didn't mention could be maxim's 4427 .

Regards Akshay,[/u]

05-21-2009, 05:02 PM
Hi all,
A whole lot of ic's http://www.discovercircuits.com/H/hbridge.htm
I don't know the price but i think this should help.

Regards Akshay,

05-22-2009, 10:45 AM
Thanks guys i think I will go with a transistor based HBridge. They are almost 5 times cheaper than L293 based ones.

05-22-2009, 12:08 PM
Transistor based bridges will not work properly at voltages less than 4V. CE drop will be too much and it will degrade efficiency.

L293D can work from 4.5V onwards. So, four pencil cells will do the job.

Max232 cannot be skipped if you want to avoid future mails saying "I don't know why serial interface doesn't works with my PC but it works with my friends PC."

Max4427 will not work, its low side driver. Also see the price on maxim's website 1.61$ each.

L293D is available for Rs50 @ cirkit electronics, lamington road.