Hi all i am working on a small project in VB, Controlling Servos by voice. everything is working great except for one thing. If i use one power adapter to control more than 1 servo, then following happens While 1 servo moves , second servo seems to get enough of a voltage fluctuation that it will move one way or the other. so currently for this to work for me, i need to have a separate power supply for each servo, then everything works great. TIA Mike
would it be possible for you to post the LPT interface circuit somewhere, so we could have a quick look? Otherwise we could all be collectively be pissing into the wind
martin
ok, well there is not much to it, i do not have a diagram, but can be easily explained. LPT ground to Servo Grounds and to 5Volts ground LPT Pin 2 out to Servo White wire (and pin3 out to second servo white wire) Both servo red wires to +5 volts
what sort of current are you using for the servos? what does it look like on a scope? where are you getting the 5V from, and how good is the supply? whats the current through the servo ground to PC ground?
martin
What kind of servos are you using? How much drive current do these servos need? (Hint: LPT ports usually can't source more than a few milliamps of current. Most have TTL or LSTTL characteristics.) Post the relevant part of your VB code.
-- Dave M MasonDG44 at comcast dot net (Just substitute the appropriate characters in the address) Life is like a roll of toilet paper; the closer to the end, the faster it goes.
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futaba rc servos using a dc adaptor to power them
Dim icount As Integer For icount = 1 To 75 Call PortOut(888, 1) Threading.Thread.Sleep(0.8) Call PortOut(888, 0) Next icount Return like i had mentioned, everything works fine if i use separate power source for each servo, if i use one power source then when 1 servo is instructed to new position then the second servo glitches alot.
thanks
Life is like a roll of toilet paper.
You buy your own they last for months.
You enter into a purchase share scheme. You will experience at least one shit a month with nothing to wipe your arse on...... after you have made your deposit.
And then they will philosophize about the origins of War!
DNA
Ummm ... sounds like a classic case of insufficient current capacity from the DC adapter or insufficient filtering. Have you actually measured the voltage level from the DC adapter under load? What is the voltage/current capacities of the adapter (should be on the label)? What are the servo voltage/current specs? Have you actually measured the current that the servos need? Have you actually measured the drive voltages from the LPT port when the servos are being commanded?
Those are very basic things that you should do, and those measurements will tell you nearly everything you need to know about your problem.
One suggestion... connect a 100uF capacitor across the DC terminals of each of the servos and see if the operation improves. Voltage rating of the capacitors should be a bit above the output voltage from the DC adapter.
-- Dave M MasonDG44 at comcast dot net (Just substitute the appropriate characters in the address) Life is like a roll of toilet paper; the closer to the end, the faster it goes.
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thanks all problem solved with resistors between servo and +5 everything is working great now thanks agin
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