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Author Topic: step up from 5VDC to 6VDC?  (Read 2548 times)

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Offline tjpark1111Topic starter

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step up from 5VDC to 6VDC?
« on: March 22, 2009, 11:35:25 PM »
im using a basic stamp 2 microcontroller on a board of education rev C to run a simple car that's supposed to go a certain distance and stop. its a competition, and it only allows me to use 4.8VDC max. however, the board of education that i have indicates that it wants 6-9VDC. i thought it would be ok and tried anyway using 4 AA batteries to power it (and the servos), but i notice the servos move differently each time i put in the same command so that my car veers left and right instead of going straight (not the same deviation each time either, and its definitely not human error). pretty much, i thought the low voltage may be the problem, so i was wondering how i could solve it. any help would be greatly appreciated. thanks!

Offline SmAsH

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Re: step up from 5VDC to 6VDC?
« Reply #1 on: March 22, 2009, 11:47:29 PM »
are you allowed to use a transformer/similar step up device? aha, i remeber now. you can use a buck/boost regulator!
« Last Edit: March 23, 2009, 12:04:52 AM by SmAsH »
Howdy

Offline Soeren

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Re: step up from 5VDC to 6VDC?
« Reply #2 on: March 23, 2009, 06:11:07 AM »
Hi,

the board of education that i have indicates that it wants 6-9VDC.
There's a voltage regulator on the board that you have to bypass, or it wouldn't have that input span.
And trying to feed a 5V voltage regulator with 4.8V spells trouble.
Bypass it and I bet a lot of your trouble will vanish.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline TrickyNekro

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Re: step up from 5VDC to 6VDC?
« Reply #3 on: March 23, 2009, 07:25:37 AM »
I recommend a charge pump to drive the microcontroller...
The servos usually operate over a wide range and should not have a problem.... (from 4V8 to 7V2)
Building a charge pump is tricky, but ensure you get the best value for money!!!

But what I really recommend which many not be so possible, is changing microcontroller...
Use an AVR and a 3V3 regulator...
Unregulated power source, with motors running on it.... it can get funky things....
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline tjpark1111Topic starter

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Re: step up from 5VDC to 6VDC?
« Reply #4 on: March 23, 2009, 06:32:37 PM »
hi, could you explain in more detail about bypassing the voltage regulator onboard? here's what it looks like: http://www.parallax.com/desktopmodules/catalookstore/ImageViewer.aspx?link=Images%2fProd%2f2%2f288%2f28850-L.jpg&desc=Board+of+Education+Development+Board+(USB)&PortalID=0&viewerid=-1&mid=-1
at the top left, there is a port for a 9VDC battery, and although the label is cutoff, right next to the 9VDC battery port theres a connector which says 6-9VDC above it. would plugging my 4.8VDC battery into the 9VDC battery port mean bypassing the voltage regulator (since it isn't a range, just 9VDC?) or would that just be a bad idea and my microcontroller would churn out smoke? thanks!

Offline tjpark1111Topic starter

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Re: step up from 5VDC to 6VDC?
« Reply #5 on: March 23, 2009, 06:52:32 PM »
wait, did you mean bypassing the voltage regulator that's regulating the power to the servos, or the microcontroller? because if you're talking about power to the servos, there is a jumper where you can set regulated/unregulated power. i would've thought regulated power would make it more stable though, as someone else pointed out...

 


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