12v to 7.2v Voltage Regulator

[SydP]

How easy is it to build a voltage regulator? I have worked with metal, wood, computors, but never with electronics. I have done some work with a soldering iron, so can use one of those. Any helpful hints . SydP

 

[Ratch]

I believe you can buy a regulator for 7.2 if your 12v is already DC (I.E. from a car).
It depends on your objective, though. If you want to charge a cell phone, etc., you'll need more than just a regulator.

 

[SydP]

Voltage regulator

Thanks Ratch. Yes the power source will be 12v DC and it is not for charging. I am motorizing a router in a table using an old 7.2v motor from a cordless drill. I have looked around in Australia but been unable to find an off the shelf reg. SydP

 

[bananasiong]

Is there any 7.2 V voltage regulator? I'm not sure. But you can get 7.2 V with an adjustable voltage regulator, e.g. LM317.

 

[SydP]

7.2v Reg

Thanks superman, but could a dummy in electronics like me, build one from an LM317? (I have looked it up and do know what it is now).

 

[ericgibbs]

Thanks superman, but could a dummy in electronics like me, build one from an LM317? (I have looked it up and do know what it is now).

hi Syd,
I think you will find that a LM317 regulator will be unable to supply the current for a 7.2V cordless drill motor.
Whats the max chuck/drill size the drill can take?
Some of these cordless motors require more that 1.5Amps when running, starting current can be much higher.

There was a long thread a few weeks ago, a guy wanted to do the same conversion.

Do a search on the forum for 'cordless'

 

[bananasiong]

oh, the load is a motor, LM317 is not a good idea for high load current.

 

[SydP]

7.2v Reg

Thanks Eric. The chuck size is 10mm, I don't need speed, but do need torque. As I have said I am new to the electronic side of things. Not really sure where to start. Syd

 

[ericgibbs]

Thanks Eric. The chuck size is 10mm, I don't need speed, but do need torque. As I have said I am new to the electronic side of things. Not really sure where to start. Syd

Hi Syd,
The LM317 is a no,no for the cordless drill.

Did you search the forum for 'cordless'?

Can you tell us a bit more about the 12Vdc power source?

Regards

 

[SydP]

7.2 reg

Hi Eric, the power supply will be an off the shelf, plug in 12v power supply. I have been told there are plenty of them about, just don't know how to get the 12v down to 7.2v. An adjustable source would be better so I could adjust the voltage to the speed/torque I need. It has got to have enough grunt to lift an Hitachi TR12 router, a heavy little beast. The planes I have for the set up, the guy used a 9v screw driver, but said any where between 3v and 9v works lovely. Just need a power supply. Yes I did run a search on "cordless", did not find any-thing of use. Will keep trying. thanks Syd.

 

[SydP]

7.2v reg.

Hi Eric, just another quick one, have you ever used the LM338T, can take a top of about 7amps. Sitting looking through some web sites and found that one. Syd

 

[ericgibbs]

Hi Eric, the power supply will be an off the shelf, plug in 12v power supply. I have been told there are plenty of them about, just don't know how to get the 12v down to 7.2v. An adjustable source would be better so I could adjust the voltage to the speed/torque I need. It has got to have enough grunt to lift an Hitachi TR12 router, a heavy little beast. The planes I have for the set up, the guy used a 9v screw driver, but said any where between 3v and 9v works lovely. Just need a power supply. Yes I did run a search on "cordless", did not find any-thing of use. Will keep trying. thanks Syd.

hi Syd,
The 12Vdc plug power supply [psu] will have to have a continous rating of about 3 to 5 amps, with a peak rating of about 5 to 7 amps, for supplying the starting current. Some of these cordless motors, as they have low voltage supplies, require high currents.
example: a 7.2Vmtr drawing say, 10amps is 72Watts, which is only about one tenth of a horse power [hp].

If you look at a mains powered router say 240Vac at 2amps, thats 480Watt about two thirds of an hp.

This example should give you an idea of the current requirement.

Does this help?
Look at this:
https://www.electro-tech-online.com/threads/cordless-drill-current-spike.29603/?highlight=cordless