AC current regulator -- help please

[Elektor Editor]

[the following query is posted 'as is' by the Editor on behalf of a reader, replies are invited]

Which IC can implement the function of "an alternating current regulator", meaning - there is alternating tension (rectangular) of a few tens of hertz at the input which should provide 100 mA constantly, keeping the same wave shape (rectangular) .

This means that it should provide constant current for any variations of the load.

The load varies within such values that it is not necessary for the tension to exceed the limits of 0.1 Vac, respectively 30Vac.

Hypothesis :
- 100 mA;
- constant;
- alternanting (rectangular) ;
- limits voltage max. 30 Vca;

who knows:
- an IC to make this function)?;
or
- a suiatble circuit diagram ?;

Best regards,
Adrian

[313002]

The first thing that comes to my mind is to try
to use the same principle as is used in Audio amplifiers.

Place a resistor of 6 ohms in series with the
both the NPN and PNP transistor output stage.
Then add a current limiting transistor on the
output transistor base.

[sjb]

In = -0V1...+0V1
Out = -0A1...+0A1
1. Voltage-->Voltage: -0V1...+0V1 --> +0V0..+0V2
2. Voltage-->Current: +0V0..+0V2 --> +0A0...+0A2
3. Place a parallel current source, '-0A1'
+0A0 - 0A1 = -0A1
+0A2 - 0A1 = +0A1

      
       ----( -> )----                //AC, 0.0..+0.2A
-----|                 |------        //Output, -0.1..+0.1A
       ---- (<- )----                //Fixed, -0.1A

[anneo]

You can try a circuit like this.Goes from 0V (short) to 30V,always 100mA.
The BD139/BD140 shout be cooled.(Max.3W each)
Sinds you didn't specify the input,calculate the R as needed.
Input current +-50µA.
Anne

[sjb]

Another possibility is the Howland Current Source.

[sjb]

Here is a Howland Current Source done in LTSpice. Choose all R the same for simplicity as Vin/I (here, 10R).

[anneo]

Very nice,now all you have to do is find an amp for +-40V at 100mA !
Anne

[thanx]

The first thing that comes to my mind is to try
to use the same principle as is used in Audio amplifiers.