Simple way to control servo directly?

You need a circuit that generates repeated pulses between 1 and 2 milliseconds long (1.5 being the mid-position of the servo). The other 2 wires to the servo are the negative and positive power supply (between 4.8 and 6v).

This is a pretty simple circuit that uses a single 555 chip and an inverter:

Otherwise, I'd suggest Googling a bit - wired R/C servo control is a very common application.

Russ.

Buy a servo tester from Astroflight for $15.

Thanks Russ. I checked out the picture (schematic) as referred, and I might try building up the gadget shown. Haven't done much electronic building lately, need to oil up my rusty techniques and this might be just the ticket. However, the other post about buying a "servo tester" for $15 probably is the more sensible option. But who ever said we gotta be sensible, especially when I spend hours hunkered down in a blind, getting eaten by mosquitoes, etc. while trying to capture a picture of some fleeting bird or deer or? ?

Olin

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Great idea, thanks for the suggestion Norm. I just looked in the latest issue of Model Aviation for that outfit, but they aren't listed at least this month. Will do a google search for them next.

Olin

If you just gotts to get solder smoke in yer eyes, surf to Tony van Roon's site has a few servo tester circuits which should serve nicely

Cheers, Fred McClellan the dash plumber at mindspring dot com

Hi Olin

It seems to me that you are intending to do it the hard way - why use a servo at all? The usual and easy way is to use a solenoid - just wire it up and use a simple push-on sw to operate the shutter - cheap as chips and twice as easy!

David

"Ol>

I used to take wildlife photos also using a remote set up.

On the first attempt I tried a solenoid but ran into wire lenght problems, ie the voltage drop across the wire was so great it prevented the solenoid from operating. You may run across the same problem with a direct servo controller, depending on how far away you want to get from your camera.

Thought about using my airplane TX/RX setup, but then I realized that the frequency was not allocated for this use, so I ended up buying an cheap RF camera remote for $50 or so, which I felt I should have done from the start!

This was about 20 years ago, so apologies for not having a source of the remote I bought, but just thought I'd put in my "2 cents"

However you do this, I wish you good luck!-)

Regards,

Frank

A relay would solve the wire length problem. Mount the batteries at the camera site and trigger the relay remotely.

How about just making your original solenoid work?

All you have to do is increase your battery voltage to overcome the voltage drop in the long cable.

Not the most efficient solution, but it will work.

Mike

An even easier one is to use FAT CABLE. Somethiung like what you use for car audio speaker wiring.

Followup to all interested and helpful comments - I followed Norm's suggestion and ordered the servo tester from AstroFlight. It just arrived today, and does the job very well. Saves me a lot of wasted time, cutting and soldering, etc. The price was actually $19.95, but that included shipping the nearly 3000 miles across country. It works equally well with almost any make of servo, and with standard control surface servo as well as retract servo. Just what I wanted. Thanks to all.

Olin

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