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# Circuit to produce 100KHz sinusoidal current (+/-500mA) is OK?

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#### treez

##### Guest
Hello,

I am making a 100KHz sinusoidal test current.
It is +/500mA peak to peak.

Is the following circuit ok?……..it simulates ok……but is it OK?

Schematic:
https://i46.tinypic.com/13z4ojs.jpg

The 0R39 resistor is the resistor on the test PCB into which I will connect the sinusoidal current....(as you see it connected here)

In the simualtor the current never goes much above 500mA, which is handy….lets hope it doesn’t go much above +/-500mA in the real circuit?

Also, the PNP dissipates 1.2W, so will need to be a power BJT……can power BJT’s switch at 100KHz?

TO220 BJT
https://www.fairchildsemi.com/ds/TI/TIP31C.pdf

...this TIP31 has a lousy gain of 10.....are there better ones out there?

(In the actual circuit, the 0R39 resistor has +/500mA sine flowing in it, and the subsequent voltage across the resistor is then amplified by an opamp, and i really want to check out if this opamp amplifies it properly.....so hence my needing this test source.)

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.lets hope it doesn’t go much above +/-500mA in the real circuit?
Hi treez
I hope so !
Also, the PNP dissipates 1.2W, so will need to be a power BJT……can power BJT’s switch at 100KHz?
Of course there are gang of transistor which are able to work in such a low frequency ! one of the options is MJ2955 !! it will handle large powers around 100 watts !
Best Wishes
Goldsmith

treez

T
Points: 2
thanks.
one problem is that the
VOH of the 555 and VOL is widely variant, and this affects the sine amplitude significantly

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here is the 50KHz (~600mA pk) sine current source so far ....(anywhere between 350mA and 1 Amp is fine)

https://i48.tinypic.com/azc9pz.jpg
(also attached)

..is there a simpler way to generate a 50KHz sine current? (of approx 600mA peak)

(sorry the original title said 100khz)

#### Attachments

• 50KHz sine test source.pdf
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