GM-20 Driver

[teknofon]

i only had a 22ohm 1w and a 56ohm 10w at home
so i tried both almost same result except the 1w got to hot

it didn't help so much

could a Schottky or germanium diode in parallel with the gm20 help?

[Banthai]

Teknofon .... top right .... white box.... type GM20 .... thats what its there for


seriously though .... we have had many a discussion here about GM20 drivers ..... both steve and Pat came up with some excellent sollutions

there is a thread here ( just to save you searching )

http://www.photonlexicon.com/forums/...highlight=GM20

i currently use a driver with an opto ( just to isolate the 12v supply from the 5v and also isolates the induced crap from the coil ) it works well and stops the twanggggg in the actuator

heres my circuit that i currently use in my projector




all the best


Karl

[mixedgas]

untitled.bmp

15 charcters................

Steve

[teknofon]

what pins should i use then?
laser fx says this
http://www.laserfx.com/Backstage.Las...Pinouts32.html
is it wrong?

[-=Jim=-]

what pins should i use then?
laser fx says this
http://www.laserfx.com/Backstage.Las...Pinouts32.html
is it wrong?

That is correct all you need are Pins 1 & 2

[mixedgas]

That is correct all you need are Pins 1 & 2

Jim is right for the newer ones.

Depends on the GM20, older ones have 4 wires and thus two coils. Mine are almost all the 4 wire, two coil version. Some newer ones with the molded in connectors have one coil. If you have two coils, generally you wire them in series.

Steve

[teknofon]

how fast can i drive the gm20?
can i drive them in say 400hz?
i´m building a color box
poor man pcaom

ps what if i bias the gm20, does it still bounce around then

[mixedgas]

how fast can i drive the gm20?
can i drive them in say 400hz?
i´m building a color box
poor man pcaom


ps what if i bias the gm20, does it still bounce around then

It will still bounce around unless you build the A102 circuit.

30-50 hz, its rated for less then 110 hz with a thin, very light chart recorder arm.

You cannot eliminate its rotor inertia or the torsion wire, so it will resonate unless electrically damped.

Steve

[teknofon]

is there a simpler way to do it?
maby with a power op-amp?

[DMills]

Sure, same basic circuit but replace the opamp and current amplifier stage with a power opamp.
Might need to fiddle with the compensation some to get everything stable.

Regards, Dan.