I have just been trying out a L293D H bridge driver on a small 12v motor and wondered if, as I only need it to control 1 motor would there be any advantage of doubling up the spare H bridge on this IC, it does seem to work but I’m not sure if it would cause problems, though I am only using it very lightly.
L293D H bridge
- Thread starter pwaggie
- Start date
terrapinlogo
Member
Yes its fine to do that many people have done it before to get more current out of the chip. some even going as far as stacking two chips on top of one another with a peice of aluminium between them to sink some heat away. If your motor requires more current than 600mA then parallel them but if it doesn't then you aren't gaining anything
IronJungle
Senior Member
What happens if you let one side of the H-Bridge chip "float"? It has never cause e ma problem, but maybe I'm asking for trouble.Remember to tie the inputs hi or lo on the other 1/2 the chip if you dont use both halves.
Just because you have swim in the ocean and not been eaten by a shark dont mean its wont happen.
The Golden rule is never leave inputs floating and even more so when you have a noisy thing like a motor in the circuit, there has been many threads about unused picaxe pins left floating, i personally do leave them floating, but normally just set them to outputs where i can.
One of the most common faults in hobby electronics is the little things like floating pins and no decoupling caps etc.
Logic often says it should all work but its often what we forgot to do and not always what we have done that causes the problems.
The Golden rule is never leave inputs floating and even more so when you have a noisy thing like a motor in the circuit, there has been many threads about unused picaxe pins left floating, i personally do leave them floating, but normally just set them to outputs where i can.
One of the most common faults in hobby electronics is the little things like floating pins and no decoupling caps etc.
Logic often says it should all work but its often what we forgot to do and not always what we have done that causes the problems.
inglewoodpete
Senior Member
While I don't fully understand what you mean by "straight through", I assume you mean "connect them all together". It is not wise to connect any pin that can accidentally be made into an output to either 0v or +5v.... and I think I shall just take all the copper tracks for input, output and ground straight through.
Yes I realise that not all pins can go straight through but most of them could, only the Enable pins and pin 8 which will go to a higher voltage source for the motor.While I don't fully understand what you mean by "straight through", I assume you mean "connect them all together". It is not wise to connect any pin that can accidentally be made into an output to either 0v or +5v.
Thanks for all the help
terrapinlogo
Member
I'm assuming you are talking about on stripboard?
Yes, in actual fact this would make the layout easier as the inputs could come in from the Picaxe on one side and the output to the motor from the other side without any crossing links. This is a rebuild of my first Picaxe project of a year ago and operates the door of my chicken house, I then later added a timer in the summer to stop it opening too soon, and a wireless link to reassure me that it was open so a consolidation of the project is called for. I used relays in the first one, and had one fail and burn out a motor, I think the H bridge will be more reliable, and I was also going to try a Tamiya Worm drive motor.I'm assuming you are talking about on stripboard?