4.5v Zipzap Dragster!!! - Page 3

fuzzy2cell · #31 02-21-2003, 07:31 AM

damn!

Wouldn't a 12v blow the circuit board or something?

wild03 · #32 02-21-2003, 09:14 AM

Quote:

Originally posted by fuzzy2cell
damn! Wouldn't a 12v blow the circuit board or something?

Oh I'm sure!

But Im bypassing the board anyways, Is the motor that worries me!

fuzzy2cell · #33 02-21-2003, 04:26 PM

Quote:

Originally posted by wild03
Oh I'm sure! But Im bypassing the board anyways, Is the motor that worries me!

LOL!!

johnrtse · #34 02-21-2003, 11:04 PM

This H-bridge concept has me intrigued. I am building a multi-cell Dragster right now and was planning to do the std. transistor mod, but had some reservations about having the weight of an extra cell in there just to power the pcb (this thing will be plenty heavy enough!).

I'll be watching this post closely, wild!

John

Project RC · #35 02-22-2003, 12:29 AM

I did exact thing as the diagram describes, but it doesn't work. How do I test it? I don't want to blow my pcb. What is the best way to test the set up without soldering it to the pcb? Help.

wild03 · #36 02-23-2003, 01:16 AM

Quote:

Originally posted by Project RC

I did exact thing as the diagram describes, but it doesn't work. How do I test it? I don't want to blow my pcb. What is the best way to test the set up without soldering it to the pcb? Help.

I would double check all the connections make sure your transistor is in the correct position. Download the specs by doing a search on "2N2222A" also those that have a metal cap, like the one I used, the cap is actually connected to one of the legs(collector) pin so make sure you don't touch the cap to any of the circuit.

The easiest way to test is to use a 1.5v battery (AA AAA etc.) instead of the PCB. By connecting the battery where the PBC would connect the motor should turn.

Oh I noticed than the colors an the diagram could be a little misleading, the 4.5v battery (+) is connected to the motor and (-) is connected to the transistor and to the negative on the PCB

I recommend testing the circuit this way before putting it on the car.

wild03 · #37 02-23-2003, 08:44 PM

Quote:

Originally posted by johnrtse
This H-bridge concept has me intrigued. I am building a multi-cell Dragster right now and was planning to do the std. transistor mod, but had some reservations about having the weight of an extra cell in there just to power the pcb (this thing will be plenty heavy enough!).

I'll be watching this post closely, wild!

John

Well, I finally got to do some rough testing and the good news is that the H-bridge actually switches back and forth, the bad news is that the thing is SO inefficient that it doesn't work.

I used a simple 4 transistor H-bridge, a pair of 2n2222a NPN and a pair of 2n2907a PNP. check this page for details.

http://library.solarbotics.net/circu...arHbridge.html

I didn't use inverters or buffers on the input so my bridge is what they call the "Bolt Light" check this page for some data on it

http://library.solarbotics.net/circu...varH_test.html

I used a 1.5v pager motor for the tests. and Power supply Vcc set to 1.506v

Vcc = input voltage
Vnl = Voltage "No Load" (no motor)
Vm = Voltage across motor
Im = Amps at motor.

First I took some measurements with just the motor connected to the power supply.
Vnl = Vcc = 1.506v
Vm = 1.488v
Im = 42mA

Second I used the simple transistor switch from my page, with a 1k resistor at the base. again Vcc = 1.506v and I used a 1.5v AA for the input signal.
Vnl = 1.487v
Vm = 1.28v
Im = 51mA

Third the "Bolt Light" H-bridge Vcc = 1.506v
Vnl = .7v
Vm = .038v
Im = 5.8mA

needless to say that with this numbers the motor didn't move. inverting the input signals did invert the Vnl voltage from +.7v to -.7v so the H-bridge was at least switching. Invreasing Vcc didn't have an effect on Vnl. I don't know why this is so, I'll have to leave it to the experts.

Project RC · #38 02-27-2003, 06:49 AM

Quote:

Originally posted by wild03
I would double check all the connections make sure your transistor is in the correct position. Download the specs by doing a search on "2N2222A" also those that have a metal cap, like the one I used, the cap is actually connected to one of the legs(collector) pin so make sure you don't touch the cap to any of the circuit.

The easiest way to test is to use a 1.5v battery (AA AAA etc.) instead of the PCB. By connecting the battery where the PBC would connect the motor should turn.

Oh I noticed than the colors an the diagram could be a little misleading, the 4.5v battery (+) is connected to the motor and (-) is connected to the transistor and to the negative on the PCB

I recommend testing the circuit this way before putting it on the car.

I got mine working now, just some soldering point problem, I redo to soldering, now they work.

CRUMB · #39 02-27-2003, 10:20 PM

two words .....thats......sick!.....

bdebde · #40 04-06-2003, 05:30 PM

Here is a link to an h-bridge:

H-bridge

It has most in german, some in english, a translator will help. I have not tried this yet, but their results look good.

charliebrown · #41 05-10-2003, 12:21 PM

Ok what it I just put the 3 LR44 's instead of the Nimh nattery and put in a high racing motor, will I still be fast?

wild03 · #42 05-12-2003, 09:43 AM

Quote:

Originally posted by charliebrown
Ok what it I just put the 3 LR44 's instead of the Nimh nattery and put in a high racing motor, will I still be fast?

Nah! Yu'll probably smoke the board!!

charliebrown · #43 05-23-2003, 09:02 PM

Well, that is why my screenname is charlie brown....I always come up with the lamest ideas...and ugh thinks HE's stupid, look at me!!!

charliebrown · #44 06-30-2003, 03:23 AM

That is one confusing mod. Can you show easier steps on how to do that nitrous system thingy???

charliebrown · #45 07-29-2003, 10:21 PM

I am VERY insulted.....is there a reason no one has replied to this thread in over a MONTH??? DON'T TEST MY PATIENCE!!!! lol ok maybe I was a li'l bit too angry sorry