AC Motor Speed Control

Thread Starter

BowTie

Joined Dec 23, 2017
9
First time poster. Sorry if any of this is in the wrong place or my post is inappropriate.
I am trying to find someone that could help me wire up a circuit for speed control of a drill motor. I purchased a set of plans online to build a piece of equipment that uses a 110v drill for the motor. He supplied a list of electronic parts and a drawing to make a pcb and what needs to go where, kind of, but a wiring diagram is non existent. I do have some pictures, but since they are his, I feel like I shouldn't post them. It has a foot pedal that has a switch that can either make the drill run full speed when the pedal is pressed or if the switch is flipped the other way, it will run variable speed. It has a micro-switch that turns the pedal on/off. It also has a potentiometer for the variable speed control. So far I have a triac, diac, a couple capacitors and some resistors of varying ohms per his design. I hope someone can help me with this. I may just be over thinking it.
 

qrb14143

Joined Mar 6, 2017
112
Is the drill motor DC?
I'm struggling to see how you could build an AC motor drive using the parts you describe. Even the most basic of setups would require a variable frequency drive which at the very least would require a rectifier and an inverter and the supporting control circuitry.

Also, you will struggle to find help if you do not provide a circuit diagram. We are not mindreaders. Even a legible hand drawing goes a long way.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
This must be for a Universal motor, there are a few out there based on Triac control of the 'Dimmer' style variety that can be purchased cheap.
I'm surprised if you purchased plans for this type, they are very simple in design and there are many out there for free.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
I purchased a set of plans online to build a piece of equipment that uses a 110v drill for the motor. He supplied a list of electronic parts and a drawing to make a pcb and what needs to go where, kind of, but a wiring diagram is non existent. I do have some pictures, but since they are his, I feel like I shouldn't post them..
You could post the link, it would give a better idea of what you have.
Max.
 

Thread Starter

BowTie

Joined Dec 23, 2017
9
Thanks for the quick replies. This is a 110v AC electric drill. As I stated, since they are his pictures, I feel I should not post them. qrb, I guess the circuit drawing is what I am struggling with. He does not provide how to hook up the switch for full/variable speed nor does he provide where to hook up the potentiometer in a circuit. I am willing to provide the drawings and pictures, just not here. Sorry for being vague with that information.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
What is wrong with the site link at least?
If you are reluctant to show anything it is hard to offer advice!
In any case, why are the vendor's not offering support?
Max.
 

Thread Starter

BowTie

Joined Dec 23, 2017
9
Max,
These are plans out of a man's garage that are getting close to 7 years old. The last time I emailed him about another question, I got the distinct impression that he did not want to support these plans any more.
 

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qrb14143

Joined Mar 6, 2017
112
I think it's best that I leave this to the people who know a lot more about this than me ie @MaxHeadRoom

In the meantime, you may find these links useful, explaining the operation of the diac and triac and how one can be used to improve the performance of the other.
http://www.radio-electronics.com/info/data/semicond/diac/diac.php
http://www.radio-electronics.com/info/data/semicond/triac/what-is-a-triac-basics-tutorial.php

If you are new to this sort of thing, you may want to look up the diode followed by the thryristor first to help you understand these more complex devices.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
Max,
These are plans out of a man's garage that are getting close to 7 years old. The last time I emailed him about another question, I got the distinct impression that he did not want to support these plans any more.
Surely you're not serious that he charged money for what you posted!
Also confirm this is a Universal motor i.e. brushed motor and not a AC induction motor, as the latter will not work with this control.
Max.
 

Thread Starter

BowTie

Joined Dec 23, 2017
9
Max,
That drawing is my crude attempt at one picture from 3 cd's full of information and pictures. The plans I bought are not for the speed controller, they are for a piece of fabrication equipment that is powered by a 120v variable speed drill. I have 99% of this completed and this piece weighs well over 200 lbs. Yes this is an AC brushed motor that also has some wiring modifications done to it.
This is the drill that is being used. www.harborfreight.com/power-tools/electric-drills/12-in-heavy-duty-spade-handle-drill-63116.html
As I have said, I am willing to share his pictures and drawings, just not here. Could I email them to you? I am sure you would look at them and be able to tell me exactly where everything needs to go.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
Also the Drill shown in the link already has variable control and reverse!.
If implementing a external type control then this would need to be bypassed, the alternative is to use the internal controller and install it in the equipment.
Do you need reverse?
Max.
 

Thread Starter

BowTie

Joined Dec 23, 2017
9
Yes It needs to be reversible. I understand the wiring mods to the drill motor, he actually done a good job on that part, and have looked at how the diac and triac work as a speed controller, just not sure where the potenetiometer and the switch to make it run full speed/ variable speed need hooked up.
 

LesJones

Joined Jan 8, 2017
4,174
The reversing switch will be a DPDT switch to reverse the polarity of the connections to the brushes. Normaly there is one field coil in series with each brush. It is done this way so the inductance of the field coils helps to filter out electrical noise from the comutator. The DPDT switch will be connected between the ends of the field coils and the brushes. It should be possible to find a suitable standard potentiometer to connect in place of the small one that is on the trigger switch of the drill.

Les.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
The vagueness is in
The reversing switch will be a DPDT switch to reverse the polarity of the connections to the brushes.
Les.
The reversing is done at the unit itself, on the foot pedal there are two switches, one is a full on overide, but it is not enabled until the foot pedal is depressed where another sw enables it, when it is off then the pedal operates the pot only, which controls speed,
So essentially the two switches overide the speed pedal.
The vagueness is in the absence of mechanical details on the pedal and the Part number for the switches.
The machine is an English Wheel.
Max.
 
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