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FlowbotX
02-16-2010, 10:26 PM
Hey everybody,

I am sure this question has been posted before but I can't seem to find it so here goes:

I have stripped down my airsoft gun to positive and negative leads. I want to control it from my ssc-32 off one of the standard servo control pins. Innitially, I thought I could do it with some old RC speed controllers I had around but they were for lipo batteries and wouldn't run off my bench power supply. Any suggestions for a simple on/off pwm controlled dc motor driver? What are all you guys using? Thanks.

zoomkat
02-16-2010, 11:45 PM
Just use the servo pin in the on/off mode to drive a MOSFET switch.

DresnerRobotics
02-17-2010, 10:47 AM
I know of a few people using these: http://www.trossenrobotics.com/store/p/5194-PicoSwitch-Radio-Controlled-Relay.aspx

gdubb2
02-17-2010, 11:23 AM
As Tybs said, some folks use the Picoswitch.

I personally use the "Team Delta" switch on Bheka, mostly because I already had a couple of older models.
http://www.robotmarketplace.com/products/0-TD-RCE200L.html

Others may use this one.
http://www.robotmarketplace.com/products/0-DGSW5.html

Lots of choices.
Good Luck
Gary

Connor
02-17-2010, 01:16 PM
I used a darlington transistor (well, I made one using two transistors, but still either way) on using the Digial On/Off aspect of the SSC-32 for the servo pin vs the PWM used for servos. Very Cheap, very easy to do. You'll need to pick your darlington transistor out and match it with a resistor so you don't pull too much amperage from the SSC-32 and blow a channel.

Thanks, Connor

FlowbotX
02-17-2010, 05:56 PM
Wow. Lots of options. I found a few MOSFETs at radio shack today so I suppose I'll give that a try but I'm going to research all these options.

Thanks for the feedback everybody:happy:

MikeG
02-17-2010, 08:25 PM
Transistors of the BJT variety are current throttles; they are not current sources. The amount of current that flows through the emitter-collector junction is controlled by the base-emitter current and limited by the power source. Transistors are great for controlling a large amount of current with a low current device like a photo cell.

FETs control current too but through an electric field, not current.

Be very very careful using the SSC as the power source and control source. While there is only some much potential available, if that potential is given a clear path to ground (saturated mode), well you get smoke.

4mem8
02-17-2010, 09:12 PM
Well personally i would and have used an opto isolater ic from the signal on the sc32 to the chip, then the out put from the opto depending on draw either direct or through a transistor resister circuit for higher current, [the normal output transistor stage]. the opto ic will stop any feedback to the scc32. always play it safe.p/s you can also convert the pulses from the sc32 servo signal to a single on off signal with another ic..If you just want pulse signals to come out the opto will work fine.

zoomkat
02-17-2010, 10:43 PM
Below is a test switch I made using a Radio Shack MOSFET, and driving it via a servo connected to an ssc-32. A logic level MOSFET would be better, but parts from RS are handy for testing.

http://web.comporium.net/~shb/pix/mosfet2.jpg

http://web.comporium.net/~shb/pix/hb1.jpg

rebel
02-25-2010, 10:14 AM
I like using the PICO switches myself

Meccano Jay
02-25-2010, 03:51 PM
Wow now i feel all low tech, i was gona use a micro servo and a limmit switch. :)