Rob-bot
USA
Asked
— Edited
Hi All,
if you are using a 12vdc linear actuator without feedback and you use a servo control board (6v - 7.2v) with a pot connected to the actuator for feedback, where would the linear actuator's 12v leads connect to being the motor outputs of the servo control board are a lower voltage?
Would you also have to have an H-bridge connected to the servo control board?
Thanx.
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*Edit: I'm logged out now, thanks @DJ
The thing is, a 12v motor can still run decently off 8.4 volts, it'll just draw more amps
The other issue is that if I were to use the lower voltage from the EZ-B to the servo control board like DJ said, the motor would definitely draw more amperage, but I believe the motor would also run much slower.
This is how you do it... 12v connects to the servo board and 6V connects to the ezb4... make sure you have common grounds between them
Do you need 6v for anything (like regular servos) because the ezb4 will happily work with 12v?
If you need 12v and 6v then have two power sources. Share the same ground.
Lastly, if you’re worried about the motor moving too slow at 6v then I would simply connect an hbridge to the servo pcb motor wires. Power the servo pcb by 6 volts and the hbridge by 12.
The servo pcb will be controlling the polarity of the two output wires that also controls the input of the hbridge.
Richard, your saying I can put 12v straight into the servo board?
"Lastly, if you’re worried about the motor moving too slow at 6v then I would simply connect an hbridge to the servo pcb motor wires. Power the servo pcb by 6 volts and the hbridge by 12. "
"The servo pcb will be controlling the polarity of the two output wires that also controls the input of the hbridge."
DJ, I see your point. Which inputs should I put the servo PCB motor wires to, on the hbridge?
I got word from our manufacturer, 8.4V is the maximum voltage the HDD servo electronics can operate at. 12V is too much.
So, I think my only choice is to wire the service PCB to Hbridge, like DJ said.
I just need to know which inputs I should use on the Hbridge.
I siliconed a 100mm 10k slide potentiometer ($3 ebay) to the flat side of a 100mm common linear actuator ($30) and drilled a small 3mm hole through the top end of the shaft at the closest part that is exposed when the shaft is retracted inside the body and used a 90 degree bent piece of wire coat hanger with small 3mm shaft collars ($1 ebay) to keep it from coming out and drilled a 3mm hole through potentiometer slider tab and using 2 part epoxy, I added a 3mm ball joint ($2 ebay) to the other end of the wire coat hanger and screwed it to the slider tab with a 3mm machine screw and nut with some liquid thread lock to keep the nut from loosening.
It gives perfect feedback to add to a servo control board and/or hbridge to use as a linear servo to connect to your EZ-B without paying over $130 for one.
You can, but for the price of 1 you can build 4.
It has given me an idea of using this, I assume 100mm ( 4 ) is the largest linear slider pot you can get? I’m based in the UK and can only find up to 100mm.
Also where did you get the linear actuator for $30?
Thanx
"It has given me an idea of using this, I assume 100mm ( 4 ) is the largest linear slider pot you can get? I’m based in the UK and can only find up to 100mm."
I think 100mm is the largest I’ve seen and I've also seen them in 75mm, and 50mm, so, you can use them for 3" and 2" actuators too.
"Also where did you get the linear actuator for $30?"
I get them on ebay.
Did you managed to get the solution i.e. (Servo/PCB + H-Bridge + DC Motor + Potentiometer) and get it working ?
I replicate the solution using a car windshield 12v Bosch Motor (Toymaker post) and all the other stuff.
if you need I can make a video.
I'm trying to connect a L12 option R linear servo by Actutronix to an L293D h-bridge chip to drive the actuator back and forth, but I'm having trouble deciding how to set it up.
The linear servo only has 3 wires unlike a DC motor with only 2 or stepper with 4. So I was curious if anybody had any ideas on how to configure the actuator. I have attached data sheets for both mentioned parts.
Thank you!
hbridge.pdf
ActuonixL12Datasheet.pdf
1 - White RC input signal (RC-servo compatible)
2 - Red Power (+6 VDC)
3 - Black Ground
If you have the option R, Dave's post is correct.
basically what you have is a Linear Servo.
You can't use a H-Bridge, you will need a micro-controller to pulse a PWM signal between 1000us (Retracted) and 2000us (extended).
I replicate the solution using a car windshield 12v Bosch Motor (Toymaker post) and all the other stuff.
if you need I can make a video. "
ptp,
that would be great if you can post a demo video. Please let me know if you do as I have not had the chance to try the components out yet and would rather start off connecting them properly.