Hi Guys,
I'm new to electronics. I'm working on a application. For that i need speed controller.

3.7v DC Coreless motor
1000mah 1C lipo battery

Initially I used POT for that, later I understood POT is not for speed controller. I came to know about PWM motor controller. The thing PWM is bigger in size for my application. I'm looking for an alternatives. More over I'm already forced to use TP4056 I don't have much room for other electronics like PWM. Can someone help me out.

Thanks in advance!

 

That would be a motor on the small size, so why is the PWM too bulky? Because it is an off-the-shelf version?
For that size it could be made quite small?

 

Welcome to AAC.

Here's where I show off my lack of knowledge with FET's:
Could this work: A supply voltage, A FET and a Pot. Use the FET in its ohmic region. Sure, that will expend a lot of energy not for the motor. Give me a few min's and I'll bang out a picture.

 

View attachment 360017
This is something similar to an experiment I did several years ago. I had a (under edit - looking for the data sheet)(OK, I can't find it. Also can't find the bag of FET's I'm looking for. I'll keep looking for it. When (if) I do I'll post it.

 

A simple controller like that would probably be better as a source follower, but I think the heatsink will defeat the purpose.

 

A simple controller like that would probably be better as a source follower

Is this NOT a source follower? Remember - I proclaimed "Ignorance" on this topic.

but I think the heatsink will defeat the purpose.

Yeah, perhaps. But maybe the case the TS has in mind can act as a heatsink.

I found some amplifier chips: B1625 and D2494 from a scavenged stereo. They're not the FET I was looking for. Some year I'll come across those again. But for now - 3.7VDC isn't going to have that much power. In part that's the reason why I thought of that large FET. wish I could find it. Came out of a hot tub spa controller.

 

No, the circuit you posted is not a source follower.

 

No, the circuit you posted is not a source follower.

OK, yeah, now it clicks - "Source Follower". I have OBS. Old Brain Syndrome. Was confused with having the FET provide the drain.

That FET I'm still trying to find - I had it on the bench. With a long wire attached to the gate, touching the insulation of the wire the motor speed it was driving would speed up. If I touched the bare tip of the wire the motor would go full speed. But when I put my ground wrist strap on and touched the insulation the motor speed would decrease. Touching the bare tip of the wire and the motor would stop.

Well, without proof I can't prove anything. So - there it is.

I recently had a flood in the basement and had to move everything around. Had to get rid of a lot of stuff too. Don't think I pitched them, but I can't find them.

 

3.7v DC Coreless motor
1000mah 1C lipo battery

How much amperage does the motor draw? Probably not much if you're talking about a small motor and a 1Ah battery.
What's the purpose? The goal? The size limits?

 

How much amperage does the motor draw? Probably not much if you're talking about a small motor and a 1Ah battery.
What's the purpose? The goal? The size limits?

Not sure about how much current draws by motor. I'm planning to make a portable fan.

 

That would be a motor on the small size, so why is the PWM too bulky? Because it is an off-the-shelf version?
For that size it could be made quite small?

Yes, I’m using an off-the-shelf PWM module right now, that’s why it looks bulky. I’m planning to make a compact custom PWM for this small motor. If you have suggestions for a minimal component design, that would be great.

 

I’m using an off-the-shelf PWM module right now, that’s why it looks bulky.

Pictures? Of the motor and other stuff.

 

The restrictive feature is the 3.7v supply.
Show the off-the shelf module.

 

Yeah, the 3.7V is the limiting factor as MaxHeadRoom said.

If you want to build small you can build this:
View attachment 360027
You will need to come up with the values of components according to your needs and desires. Without knowing the current draw of the motor we can't recommend a transistor. Not unless you want us to assume your motor is one of the motors salvaged off of the Titanic. OK yes, quite a bit overkill. But it should drive home the point.

If you can find a 555 that can operate on 3.7 volts then the above circuit may provide the control you want. Again, we know nothing about your project except that you want to build a variable speed fan. Even if you could tell us the make and model of the fan you have that would help us do some of your research for you. With that low a starting voltage D1 & D2 should probably be Schottky diodes. They have a lower forward voltage drop. And that might be a critical factor in making this whole thing work.

I made something similar to this to control a 12 volt air injector fan. It blows air into a firebox giving the fire a greater supply of fresh air. But I can't find that circuit either. It's around here on this computer - hopefully. The computer I originally used crashed. I was able to extract the hard drive and download its contents but I think that's on another computer.

 

View attachment 360028
Source: https://search.yahoo.com/search?p=555+circuit+that+runs+on+3.5+volts&fr=yfp-t&fr2=p:fp,m:sb&fp=1

 

And remember - over time your battery voltage will be dropping. At 2.8 volts you should consider your battery to be dead. Dead but still rechargeable.

THAT brings up more questions: How are you going to charge your battery? Will your battery have a BMS (Battery Management System) to control charging and shut the battery off at 2.8V?
Failure to manage your battery properly can lead to smoke, fire and lots of excitement. Maybe even meet some nice firefighters.

 

Hello,

The cmos version of the 555 can work down to 2 volts.
The output current is lower than the bjt version.


The output current is dependend on the supply voltage:


Bertus