Variable output DC power supply
- Thread starter zendriver
- Start date
cvairwerks
Well-known member
To get 100 volts and significant amps, you are going to be spending multiple kilobucks for a variable supply. A Lamda Gen 2U 3300 watt supply is going to get you back nearly $4K.
tool_scrounge
Well-known member
Buy a used dc motor driver on eBay from minarik, dart, etc.
If you don't needed regulated AMP.... like most lab power supply that can variable volt and amp...
you can always consider building a custom one out of a variac ... . ebay have those variac pretty cheap, and a 30AMP or 2 30 AMP bridge rectifier, + a matching capacitor (needed to be 350V and above )? like a traditional old style power supply? Hey you can even make it variable both ac or dc.
you can always consider building a custom one out of a variac ... . ebay have those variac pretty cheap, and a 30AMP or 2 30 AMP bridge rectifier, + a matching capacitor (needed to be 350V and above )? like a traditional old style power supply? Hey you can even make it variable both ac or dc.
Last edited:
byoungblood
Well-known member
What is going to kill you is the current capacity. I work on stuff with vacuum tubes so I regularly deal with 300-500v transformers, but they're only needing to supply 100-200mA at most.
While using a variac and bridge rectifier would technically work in a pinch, problem is that capacitors to remove a sufficient amount of ripple at the currents required are going to get expensive quickly. I built a 3-30v@3A bench supply and I have about 44,000uF of capacitance to keep the ripple within limits under maximum load. Just doing some rough calculations, if you couldn't tolerate more than 1v ripple at say, 120v, at a 15 amp load, you're going to need about 42,000uF capacitance. Next typical value is 47,000 uF@160v, and an in stock Nichicon is $150 at Digikey.
Now, if all you are doing is testing to see if the motors will start, or they can deal with say, a 5v ripple, then you can size down your filter caps quite a bit. But if you're testing under load, you're going to have to open up your wallet.
While using a variac and bridge rectifier would technically work in a pinch, problem is that capacitors to remove a sufficient amount of ripple at the currents required are going to get expensive quickly. I built a 3-30v@3A bench supply and I have about 44,000uF of capacitance to keep the ripple within limits under maximum load. Just doing some rough calculations, if you couldn't tolerate more than 1v ripple at say, 120v, at a 15 amp load, you're going to need about 42,000uF capacitance. Next typical value is 47,000 uF@160v, and an in stock Nichicon is $150 at Digikey.
Now, if all you are doing is testing to see if the motors will start, or they can deal with say, a 5v ripple, then you can size down your filter caps quite a bit. But if you're testing under load, you're going to have to open up your wallet.
pilotmotor
Well-known member
- Joined
- Mar 13, 2018
- Messages
- 88
If the motors are the universal type , with wound fields , than ripple is not a concern. They will even run on A/C.
Shiftless
Well-known member
Why not wire up some car batteries in series? That would give you steps of 12 volts each. Your choice of 12,24,36,48 and so forth. No ripple.
You could draw lots of amps at least for a little while.
I would use a big fuse in the circuit to give you some protection from accidents.
Maybe even shields over the batteries for personal protection.
You could draw lots of amps at least for a little while.
I would use a big fuse in the circuit to give you some protection from accidents.
Maybe even shields over the batteries for personal protection.
American Locomotive
Well-known member
The cheapest way to do it will be to purchase a 0-90v DC motor controller/driver on e-bay.
The motor I'm trying to test now is a "2 1/2 hp" treadmill motor that is 90 V I forgot the amps.
Just for the hell of it I quickly looked it up to a car battery and it jumped off pretty good, I just like to find a better way to test.
I haven't really worked on electronics in 35 years so most of it is forgotten.
I'll look into the motor controllers
Sent from my iPhone using Tapatalk
Just for the hell of it I quickly looked it up to a car battery and it jumped off pretty good, I just like to find a better way to test.
I haven't really worked on electronics in 35 years so most of it is forgotten.
I'll look into the motor controllers
Sent from my iPhone using Tapatalk
Shiftless
Well-known member
What is your intended application for the motor?
You know that it isn’t dead, so go ahead and mount a pulley and install it on your drill press or whatever you plan to use it for.
Drill press? Go cart? Winch? ?????
You know that it isn’t dead, so go ahead and mount a pulley and install it on your drill press or whatever you plan to use it for.
Drill press? Go cart? Winch? ?????
Not sure. Right now a family member needs a new motor for their treadmill and I think this one will fit.
Never thought about powering a drill press.