Review: RobotKits.co.in two channel Darlington transistor H-bridge
August 17, 2014
This is a short review of the RobotKits.co.in two channel Darlington transistor H-bridge.
Early last year, I picked up a few items from www.robokits.co.in. One item I saw was the 5amp Darlington motor driver. It was only $5 USD and had two channels rated at 5amps each. I added it to the cart with the rest of my order and waited. In about 8 days, the carefully packaged parcel from India arrived safely to my door.
The driver came with no paper work, but did have a well marked silk screen on the board.
The board seemed very well made, and all the soldering looked good.
Each channel has 2x TIP122 and TIP127 darlingtons and 2x logic switching transitiors. The board also has 5v (7805) regulated power out. The motor votage max in is 18v dc.
It can be driven by 3.3v or 5v logic, so will work for a wide range of uC's. The drive logic table is on the board and can clearly be seen:
You probably get @1.5v voltage drop, as far as I can tell, though I have not done any testing. The 12v motors on my test platform seemed to run fine with a 11.1 lipo.
Now this board does NOT have any logic chips to drive the transistors with. You do not want to drive both of the channel inputs HIGH. One needs to be LOW and the other PWM or HIGH (if you are not doing any speed control) There is also no diode protection on the board.
All the testing I did was on my old test plywood chassis. I ran it with both a 7.4v and 11.1v lipo. The motors/driver did fine with both. I used a Mega I have on the chassis to drive it and a Generic motor driver library I wrote for Transistor and relay h-brigdges. The class does not allow for two highs on a channel, so gives you code protection from short circuits.
I would recommend this driver for robotic intermediates and above. It would be a good replacement for L293/L298 boards if you have motors with a little larger current draw. It's cheap, well made and relatively easy to use. It's usable by a wide range of micro controllers due to it's 3.v-5v logic driving range. A set of functions to drive it should be very easy to write in any language.