Waveform amplifier problem

[Razak]

I have posted on here before and received some very useful help on setting up an amplifier circuit for an arbitrary generator to increase the voltage output. The circuit works fine under testing with a multi meter.

The DUT draw a short spike of current of around 500mA when actuating a valve, and the OPA547 can supply this continuously and spike up to 750mA. However when attempting to actuate the valve when the DUT is powered though the amplifier circuit, it draws 150mA and fails to open the valve, there is also a large voltage drop (from 12v down to around 1V while the valve trys to open.

Ive attached a basic diagram of the set up i have atm, any critique or ideas would be highly appreciated, ive not had any training in electronics or the like so silly errors are more then likely

 

[Harald Kapp]

It would be helpful to know how the DUT looks inside (schematic).

What waveform dio you use? Is the DUT rated for that waveform?

Note that the OPA547 can deliver only V(+)-2.2V at 500 mA current. This voltage may be too low for the DUT to turn on correctly.

 

[Razak]

It would be helpful to know how the DUT looks inside (schematic).

What waveform dio you use? Is the DUT rated for that waveform?

Note that the OPA547 can deliver only V(+)-2.2V at 500 mA current. This voltage may be too low for the DUT to turn on correctly.

Even just using a steady DC current i have the problem. as for a schematic, i cant give that as it is unknown to me.

I must of missed something in the datasheet, i didnt see anything about only being able to supply 500mA at 2.2v i thought it was alot higher

 

[Harald Kapp]

500mA at 2.2v

Not at 2.2V, at V(+)-2.2V, meaning 9.8V with a 12V supply.