# Small linear motor power supply amplification

#### BragaV

Joined Jul 23, 2020
3
Hello,
I am new to the forum and looking for assistance.

I am trying to create an AC voltage source (sine or square wave) that provides a current of up to 200mA, between frequencies from 1Hz to 500Hz. So far I've been using a wave generator that can generate waves at the desired frequencies, but its maximal output voltage is 10Vpp, whose current in the circuit is 87mA.

So, I was thinking about how to make the chain the desired value. Should I amplify the signal from the generator? If so, how? Because I looked for some amplification circuits that don't seem to work at low frequencies. Another option I saw here on the website was to create an inverter, but the circuits I found online are high voltages.

Any suggestions, comments, circuit diagram that you may have, I appreciate it

#### AlbertHall

Joined Jun 4, 2014
11,712
What output voltage do you need?

#### Audioguru again

Joined Oct 21, 2019
4,129
Use an audio power amplifier, but increase the value of its coupling capacitors so that it produces frequencies down to 1Hz.
Hey. 1Hz is a heartbeat!

#### MrChips

Joined Oct 2, 2009
25,061
What you need is not so much a voltage amplifier but a power amplifier. You do that by reducing the output impedance of the amplifier. You can accomplish that by adding transistors at the output stage or you can use LM675 which can handle 60V supplies and drive 3A. DC-couple your signals in and out for 0Hz - 1kHz performance.

#### BragaV

Joined Jul 23, 2020
3
What output voltage do you need?
Hello AlbertHall,

I've been controlling it mostly by the current so i'm not really sure what is the voltage needed. With 10Vpp I measure 87mA, so if I could go to 15Vpp or 20Vpp I think would be enough.

#### BragaV

Joined Jul 23, 2020
3
What you need is not so much a voltage amplifier but a power amplifier. You do that by reducing the output impedance of the amplifier. You can accomplish that by adding transistors at the output stage or you can use LM675 which can handle 60V supplies and drive 3A. DC-couple your signals in and out for 0Hz - 1kHz performance.
Thanks MrChips for the advice. I try out this two approaches and see which works best

#### Irving

Joined Jan 30, 2016
2,424
I'd second the LM675, I've used one for much the same, to drive a vibration motor at a controlled amplitude/g-force.