I have come across this circuit for a simple dc motor control. Does anyone have any input. I need something simple for speed control. high precision is not needed. Thanks.

 

The image is too small to see, and you have not provided any info about your motor or supply voltage.

 

Is there a "best way" to post the circuit. I scaned it from the article. I can redraw it and scan again? Or another method?

 

What voltage/current does your motor require. That drawing shows 120v ac going through a bridge rectifier. Very dangerous..

 

It is a 90 volt dc dayton motor. I do not have the current requirements with me. I was going to use it on a grinder in a home shop. Why "very dangerous"

 

Check post by hobbyist, right now two posts below yours. He is using 90V PM motor with a SUS trigger; schematics almost the same. The DIAC will trigger at about 28V & SUS adjustable, as shown about 10V. An isolation transformer will keep from having a " hot chasis".

 

I hope this is a better image. My motor is a 90volt 1amp continious duty permanent magnet motor. This circuit came from "The Home Shop Machinist" Charles Eyer 1996. The idea was to use a dc lawnmower motor on machine tools for speed control instead of belts. I was wondering if it still is viable or is there another equally simple cuircut that can be used?

 

The circuit is simple & should work. I would connect motor to moving SW contact, fixed to R2 & B1+, other SW to black 115 AC line along with a 10A fuse. Ground motor frame & chasis if metal. Remember all of the accidents back in the 1950s when when we had high V series string filaments & hot chassis; be carefull if not using isolation transformer.

 

What is a moving SW contact? If you have any other simple designs I am not commited to this one. How would an isolation transformer fit in?

Thanks for the input!

 

Not pretty, but I hope it helps: The transformer willnot make ckt work any better, but adds a bit to safety, @ 150W, probably expensive. There are a lot of appliances that use two wire cords & no transformers, but are designed to keep wandering fingers away from hot circuits.