# Anyone know of a 9V to 12V DC-DC converter?

I'm trying to find a DC-DC converter that takes an input of 9 volts and outputs 12 volts, with atleast 300ma of output current. Using a 9 volt to 5 volt then 5 volt to 12 volt I could get the right output, but I'm trying to save as much power as I can as the battery is shared by the motors and that wouldn't be particularly effecient (and would take up more room in the 'bot). Any suggestions? I haven't been able to find one anywhere online..

## Comment viewing options

its really easy to make voltage doublers, a few parts from a computer power supply and  maybe a crt monitor are about all ya need (carefull you can get killed by a charged crt)

simply build.... ..... ......hmm....

ok... uh I cant find my schematic for this....

basically, it uses a 7414 as a squarewave oscillator with a 50% duty, drives some transistors that push pull a centertapped coil, each end of the coil goes to a diode to your output cap, because the center of the coil is at V, grounding one end of the coil causes the other to go up to 2*V you can use the linked inductor they use in mains filters, because the circuit only has to generate half the voltage, its output power is really high.(if your output is 24V at 2A, (48W) the circuit is only generating 12V at 2A (24W))

because it can be made rather small, I use it to generate coil voltage for all those stupid dime-a-dozen 24V relays.

I have used a variation of this to boost 12V to 18V for running a laptop on one of my robots.

If you are interested, look me up, and I'll make/find/post a schematic.

http://eds.dyndns.org/~ircjunk/robots/mowerbot/dscn9634.jpg  <-- relay driver

http://eds.dyndns.org/~ircjunk/robots/rovbot/dscn1026.jpg <-- laptop voltage booster

Well, turns out I'm totally wrong. I'm not home currently so I was going by memory, but after phoning for someone to check, it's actually a 6v battery...I'm fairly certain I can easily find a DC-DC converter for 6v to 12v. I'll get back to you folks on that. (I thought I had found a 9v RC pack and was using it to gain faster speeds from the motors, which other sites said worked fine.... but I didn't...)

Its a 9 volt RC car battery, so alot more power than a standard 9 volt (I think around 2300mah) . The motors are actually 9 volt, but I need 12 volt for the video transmitter I'm putting in it. Although I actually could find quite a few 12v TO 9v DC-DC converters, so I suppose that I could try to find a cheap 12v battery with decent power. (Couldn't find a cheap one) I COULD just use a bunch of rechargeable AAs though, would work fine I guess.

yep, get a 12 v battery, use it directly for motors, and with 7805 for electronics, better yet, use two different batteries to avoid weird behavior.

I would assume you have 12v motors and you are running both brains and motors off of a 9v battery? If so, this is probably a no-go. 9v batteries don't have much capacity. That capacity gets used up even quicker when stepping up the voltage. I have seen a lot of people go by here trying to run both motors and brains off of one 9v and I have to say, I have only seen it work on very small robots.

If I am wrong here, and you still need 12v from 9v, I would check out spark fun --they have some dc/dc converters and might have one that outputs 12v.

Why not use a 12VDC power source? You are taking the 9VDC down to 5VDC, so there's waste there, then you want to take 9VDC to 12VDC, which is more wasted power. If you used a 12VDC source and used a 5VDC regulator, it would save you power, and the increased power capacity of the 12VDC would easily defeat any 9VDC battery.