Hello, newbie electronics here,
I have a 5V DC motor (a dog shaving machine), where I had to by pass the electronic circuit that died and solder the wires directly from the source to the motor (DC 5V converter). I noticed that the motor starts slow with this arrangement and in about 5 seconds it picks up to a full speed. This is when there is no load attached to the motor. However, when the same load as before (shaver head) is attached, the motor almost stalls. Now this is the same load on the same motor as before that worked. Does anyone know how to reinstate the torque without a new board?

Thanks
Amir

 

Sounds like it is swamping the supply at first start up due to maximum current.
You need a small 555 controller, can be had off ebay for a couple of $$.
Or simple to make up oneself.
Max.

 

Sounds like it is swamping the supply at first start up due to maximum current.
You need a small 555 controller, can be had off ebay for a couple of $$.
Or simple to make up oneself.
Max.

Thanks, I'll look for one, any specific reliable you may know of?

 

$1.50 one https://www.ebay.com/itm/Mini-DC-5A...836155?hash=item281b3f77fb:g:HwUAAOSw61haWaOV
Or to make one, http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm
Max.

 

$1.50 one https://www.ebay.com/itm/Mini-DC-5A...836155?hash=item281b3f77fb:g:HwUAAOSw61haWaOV
Or to make one, http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm
Max.

Thanks

 

Wonder if the motor requires a higher voltage. The controller board may be a step up DC to DC converter or a DC to AC converter. Would need to check the label on the actual motor if there is one. What is the brand and model number of the shaver?

Steve G

 

Wonder if the motor requires a higher voltage. The controller board may be a step up DC to DC converter or a DC to AC converter. Would need to check the label on the actual motor if there is one. What is the brand and model number of the shaver?

Steve G

Nope, in fact, the original output from the board was DC 3.6 V and the motor ran just fine under the same load. Unfortunately, there are no information whatsoever printed on the motor itself. I soldered a ceramic capacitor to the leads, which helped smooth a bit, but it would still almost stall with load attached. I have ordered the controller Max suggested, lets see what happens when I hook them up.

 

You could also check the motor on a higher capacity supply, or 4.5v - 6v from AA cells etc.
Max.

 

You could also check the motor on a higher capacity supply, or 4.5v - 6v from AA cells etc.
Max.

I did with 5 volt, starts up slow and picks up in a few seconds - no load, and stalls under intended load.

 

Sounds like you have some friction problem somewhere, is there gearing or any reduction mechanism?
Particularly with shaving hair!
Max.

 

I did with 5 volt, starts up slow and picks up in a few seconds - no load, and stalls under intended load.

Was that with a different power source?
SG

 

Sounds like you have some friction problem somewhere, is there gearing or any reduction mechanism?
Particularly with shaving hair!
Max.

There are no gears, it is a simple process, the motor head has a small off-center pin that sits in an open, U shape slot when the shaver head is pushed in. As the motor turns, the small pin hits the two sides of the U channel and makes the blade move right and left. I was able to rule out the mechanical issues. I am hoping the controller would help (no big deal if doesn't, as I have other projects I can use it for).

 

Was that with a different power source?
SG

Yes, a converter (the same one I am using to connect directly) used to charge a 3.6 V battery which was the power supply. Original battery died and so did my replacement from ebay in a couple of months. I decided to by pass the board that charged the battery and connect the converter wires directly to the motor. As I said, with no load, it spins just fine (but starts slow), but it seems like there is not enough torque when the load is applied without the electronic board. No gears or pulleys, nothing was ever removed from the assembly except for the circuit board. Maybe the converter doesn't have enough amperage for my unmarked motor???

 

Yes, a converter (the same one I am using to connect directly) used to charge a 3.6 V Maybe the converter doesn't have enough amperage for my unmarked motor???

Exactly! It's designed only to charge the battery. You should have mentioned that in your first post.
SG

 

Exactly! It's designed only to charge the battery. You should have mentioned that in your first post.
SG

Not exactly, I had it working without the battery using the same circuit components.

Anyway, It turns out the wall converter was only supplying 1000mAh at 6v, where I needed about twice the amperage, problem solved.

Thanks for everyone's input.