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a question on electronic stuff for DannyMax :)
show user profile  jareu
Hopefully you get to see this, I need a lil advice with the H-bridge we talked about in the laboratory thread, I built something like this:

basically I put two of these back to back but when I supplied the 50 volts, without having any of the transistors' bases connected yet, two of them went red hot. I checked for bad connections and short circuits etc, but it all seemed to go according to the first diagram.

I'm using 8x high amperage high speed switching transistors, and 8x high power diodes. It does seem a lot just for one motor, do you think I'm doing it right?
I really appreciate your help. I'll soldier on tomorrow and see if I can't get any decent results

He who says it cannot be done is interrupting the man doing it.

read 558 times
11/21/2011 3:20:46 PM (last edit: 11/21/2011 3:20:46 PM)
show user profile  DannyMax
I'm at work right now mate so cant look at this just yet , I will have a look and help you out when I get home tonight , should be about 20:00 uk time. what I will say is have a look at the L298N driver IC it will run up to 3Amp loads should cost no more than £4 or £5. but if you stay with the transistors make sure you bias them with a resistor to keep them turned off, by the sounds of it you have the base's of the transistors floating , this could turn them on at random causing a short across your main power supply and that can blow both the PSU and your transistors.

good to see your working on it :)
chat later

read 546 times
11/21/2011 4:46:44 PM (last edit: 11/21/2011 5:11:11 PM)
show user profile  jareu
cheers man, I should have used resistors. I will take a look at the L298N IC, I'll let ya know how I go :)

He who says it cannot be done is interrupting the man doing it.

read 515 times
11/22/2011 3:05:32 AM (last edit: 11/22/2011 3:05:32 AM)
show user profile  jareu
edit: double post

He who says it cannot be done is interrupting the man doing it.

read 514 times
11/22/2011 3:10:20 AM (last edit: 11/22/2011 3:10:35 AM)
show user profile  DannyMax
Sorry i did not get back to you last night I ended up not getting back till 4 or there abouts :( . let me know how you get on :)

read 502 times
11/22/2011 11:19:07 AM (last edit: 11/22/2011 11:19:07 AM)
show user profile  jareu
all good man, I appreciate any time you can give :)
I went down today, got some new components and started again. Still can't get any results.

Same configuration as before, but this time with a 1k ohm, 1 watt resistor on each base of the transistors, and another on the +30V line for good measure. This time nothing blew, but I noticed that with no voltage on the +30V line, and 5Volts on the two opposing Transistors (this is just one H-bridge, so that I could test my circuit design) to emulate a microcontroller output, the thing drew 2.5 amps and the resistors heated up pretty quickly, so did the two bottom transistors. (the ones connected to ground)

I turned it off, let it cool down and then set the PSU to +30V and +5V and turned it back on with a multimeter where the the motor should be. I read 0.00V on the multimeter but this time there wasn't much heat on the resistors and the top two transistors heated up.

I'm at wits' end at the moment, but I'm guessing I'm using the wrong switching transistors. I'm using the TIP122 (NPN) medium power, high speed switching transistors. Thanks again for your help, I'm pretty new to technical electronics and attempting to branch from software and firmware design into a fully functional machine is pretty challenging for me :)

He who says it cannot be done is interrupting the man doing it.

read 489 times
11/22/2011 2:42:36 PM (last edit: 11/22/2011 2:46:02 PM)
show user profile  DannyMax
Hi jareu if you PM me your Email I will send you some info I have on the H-bridge I made with some power transistors, it was some time back now but I'm sure i got the info still.

read 481 times
11/22/2011 3:03:56 PM (last edit: 11/22/2011 3:04:26 PM)
show user profile  jareu
cheers man, I owe you one, email is jamie at

He who says it cannot be done is interrupting the man doing it.

read 472 times
11/22/2011 4:05:52 PM (last edit: 11/23/2011 1:28:26 AM)
show user profile  DannyMax
cool I will do that when I get home .. you may want to edit your post to something like jamie at just in case :)

Emailed you dude ,the transistors on ther low side (bottom two) should be PNP types' not NPN sorry I missed it before.

read 461 times
11/22/2011 6:15:50 PM (last edit: 11/22/2011 10:56:53 PM)
show user profile  jareu
cheers for your help, I used the circuit you emailed me, simplified it a little for the sake of experimentation, but it works beautifully now. Ironically the stepper handling program I wrote won't program properly on my pickit3, keeps getting 'not ready for debug' error. I'm pretty sure its broken.

Once I get a new one and a new chip (its pretty old) I'll keep y'all updated :)

He who says it cannot be done is interrupting the man doing it.

read 425 times
11/28/2011 7:18:34 AM (last edit: 11/28/2011 7:18:34 AM)
show user profile  DannyMax
cool :)

read 418 times
11/28/2011 9:59:02 AM (last edit: 11/28/2011 9:59:02 AM)
show user profile  jareu
ok, need ur help again :)

The circuit works beautifully, but now I'm having trouble with my PIC's misbehaving...

I'm using a PIC18F, namely a 18F4410, and I'm finding that out of all 5 ports, only two are doing what they're told, and even then only half the time.

I ran a program moving 0xFF to PORTA, PORTB, PORTC, PORTD and PORTE and found that only PORTD and C are holding 0xFF. the rest are showing 11010000 or 00100000.

then I tried to use PORTC as an output, setting bit 1 and clearing bit 0, running a delay, rotating the byte right, running another delay and rotating the byte left.

what I should have seen was this:

looped infinitely. This worked at first but after the first couple of runs it started doing this:

no idea why bit 1 stayed that way instead of being rotated right.

anyways, just wondered if you had ever had any ports misbehave on you. I was so close to having this damn motor spinning, but now the circuit is shorting because of this problem :/

He who says it cannot be done is interrupting the man doing it.

read 393 times
12/8/2011 6:46:23 AM (last edit: 12/8/2011 6:46:23 AM)
show user profile  DannyMax
sounds like a port read/write problem to me but I would need to see the part of your code that writes the data to the port . Im at work right now so may not have time to do anything but when I get home I will take a look if you email it to me , or post a few lines of it here. dont forget write to the LAT, not the PORT writing to the port can cause all sorts of problems, the Lat register is the right way to send data out to a port. so to write to PortA you would code " LatA = 255" as Im sure you know this will make all the pins on port A high. anyway hope this was some help if not as I said before email me your code if you like and I will have a look when I get home.

read 378 times
12/9/2011 1:35:47 PM (last edit: 12/9/2011 1:50:14 PM)
show user profile  jareu
wow I had no idea about the lat, I've been using ports this whole time! anyways, I unplugged it and let it chill out for a while, it works beautifully now.

I made a LED controller which smoothly gradients three groups of red green and blue LEDs to get 6 colours. Looks amazing! Once I've gotten it soldered together properly, I'll post a vid.

Once again I really appreciate your help!

He who says it cannot be done is interrupting the man doing it.

read 364 times
12/9/2011 5:09:35 PM (last edit: 12/9/2011 5:09:35 PM)
show user profile  DannyMax
no probs dude , good to hear your getting to results :) looking forward to the vid

read 349 times
12/9/2011 9:51:21 PM (last edit: 12/9/2011 9:51:21 PM)
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