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I am working on a project in which I need to use a preloaded value to vibrate a transducer. So loaded required values into Arduino Uno, converted into analog values using R-2R DAC and buffered values using ua741, all should work in 5 volts. Now the problem comes:

I need around 300mA current to drive the transducer (resistance is 10-20 ohms) can you please suggest me a transistor (preferably BJT) which gives particular current in 5 Volts power supply?

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  • \$\begingroup\$ Not sure what you mean. Do you just need to boost the current out of the op-amp? \$\endgroup\$ – Icy Jan 8 '16 at 8:24
  • \$\begingroup\$ Hi Icy, I am using op-amp to remove the loading effect (hope I am correct theoretically) and trying to boost current by some other means. Please let me if any other alternatives. \$\endgroup\$ – user96468 Jan 8 '16 at 8:51
  • \$\begingroup\$ Link to the transducer. It's possible that it only needs a specific DC voltage, with at least 300mA available - a much simpler problem. But without data, who knows? \$\endgroup\$ – Brian Drummond Jan 8 '16 at 12:04
  • \$\begingroup\$ I do not have any link to the transducer, but I have one old device for which I can access the pins which vibrates the transducer. Upon measuring with the device's usual settings it requires 300mA and the voltage peak to peak was 7.8V. As I mentioned I need to reduce the supply voltage to 5V, so please, any help is truly appreciated. \$\endgroup\$ – user96468 Jan 9 '16 at 4:38
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schematic

simulate this circuit – Schematic created using CircuitLab

TIP31 seems a good choice, but the 741 is going to need more than 5V for its supply.

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  • \$\begingroup\$ Thank you very much, Sir. The datasheet of ua741 says the supply range is +18V to -18V and my input will be 2.5 volts at the maximum. Can I still use the same OPAMP or need to change it? My constraint is, I have to use the 5 volts supply and not more than that. \$\endgroup\$ – user96468 Jan 8 '16 at 6:10
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    \$\begingroup\$ @user96468 use a LM358 then. It's as cheap and old as the ua741 but better suited for single supply operations. It will work with 5V supply. Voltages at the inputs of it should be within 0V to 3.5V, not higher. So if your Arduino Uno has 5V IO voltages you'll need a voltage divider. \$\endgroup\$ – Nils Pipenbrinck Jan 8 '16 at 8:01
  • \$\begingroup\$ Thank you very much Nils Pipenbrinck, I will use LM358 and make sure input to be within 3.5V. \$\endgroup\$ – user96468 Jan 8 '16 at 8:57

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