Tip147/142 or Tip137/132 H-Bridge a good idea? - Page 1
Forum section: electronics / beginners

author: cart
author_rank: Contributor
timestamp: February 26, 2013, 08:03:39 am
content: Hi Guys.This is my first post here.Ive been at quite allot of EE Blogs but they seem a bit died out so I hope you guys can help me.I want to drive a 24V motor and the load that the motor will push up/pull down will be toughly 30Kg.So I thought of building a H-Bridge that would be capable of handling high amps and also 24V +/- .Will the Tip 142/147 and/or Tip 137/132 suffice? Also will they switch on with a 5V signal from a microprocessor directly on to their pins(which probably isnt a great idea) or optoIsolators 5V?I have read the datasheets but I am still unsure and im in doubt because this is a project that should work for a very long time.Thanks guys

author: cart
author_rank: Contributor
timestamp: February 26, 2013, 09:36:20 am
content: Ahh yes of course.Knew I missed something.Ok well my HIGH amps would be 10A max.I know that isnt to high but im low-voltage elec guy and that quite allot to me :s.

author: fcb
author_rank: Super Contributor
timestamp: February 26, 2013, 09:52:16 am
content: You don't mention if you need variable speed control (PWM), but either way I would use N-channel power mosfets inplace of transistors - lower losses and simple drive circuitry.If you just need simple up/down control use a single BUZ11 mosfet and a relay to switch direction (i did this for a customer 20 yrs ago, there still using the same design now with very low FIT rate thanks to the 'soft-start' of the mosfet giving the relay an easy ride).

author: cart
author_rank: Contributor
timestamp: February 26, 2013, 10:10:10 am
content: Yes the motor has no PWM at the moment.Simply start and stop.Do you maybe have a schematic?Thanks

author: ignator
author_rank: Regular Contributor
timestamp: February 26, 2013, 10:18:41 am
content: Quote from: cart on February 26, 2013, 10:10:10 amWhats your power supply? What voltage or voltages? If all your doing is bang-bang control, you don't need a H drive interface, these are used where precision bi-directional control is needed (closed loop motor control).If you have a plus and minus supply, you can ground one lead of the motor and just switch + or - power to the other lead. Or if only single supply, use polarity switching relay and single switch as fcp indicated.ignator

author: cart
author_rank: Contributor
timestamp: February 26, 2013, 11:24:16 am
content: The motors voltage is 24Volts and needs to get supplied by 24 and -24 volts.It needs to be switched on and off by n MCU which works at 5V typically.What do you call that tipe of relay?You give the Relay 24V and depending on which switch you make high with 5V? 12v? it flips the voltage?

author: Kremmen
author_rank: Super Contributor
timestamp: February 26, 2013, 11:40:06 am
content: Easiest solution: use 2 regular power relays to switch on the motor. One relay runs the motor this way and the other that way. A simple N-channel logic-level FET to drive the relay coil. The FET gate can be connected directly to an MCU output. The one (big!) caveat is that you must guarantee that both relays are _never_ enegized simultaneously. Can be done by using auxiliary relay contact for cross locking one out while tghe other is on.Alternatively, use one DPDT relay to select motor polarity and another SPST relay to switch on the supply. First select direction and then turn on power. Cannot short circuit the supply that way.Or, replace the SPST relay with a power MOSFET (from motor to ground) and connect the supply circuit that way. Check the attached document showing an Arduino controlling the last alternative. It is unfortunately in Finnish, but you will get the idea easily enough.

author: ignator
author_rank: Regular Contributor
timestamp: February 26, 2013, 06:36:23 pm
content: Quote from: cart on February 26, 2013, 11:24:16 amcart:What is your electronics skill level? Do you know how to bias an open collector/drain transistor switch?Please indicate if you understand this, as this group can be very helpful with schematics if this is the level of input needed.ignator