I fount two old gold leg 2N5458 jfets in a bag of parts and now i wonder if i could use them to anything.
first: download the datasheet and identify the leadouts.
second: assemble an Idss measuring jig. 9V battery, 1k0 1% resistor, set of 3 croc ended leads.
third: measure the Idss at your actual test voltage.
This confirms you have working jFETs, it also gives an idea of what type of circuit would suit them.
second: assemble an Idss measuring jig. 9V battery, 1k0 1% resistor, set of 3 croc ended leads.
third: measure the Idss at your actual test voltage.
This confirms you have working jFETs, it also gives an idea of what type of circuit would suit them.
First, already done, thats how i found out they were jfets.
Second, does 1k go betweek G and D or G and S ? i dont have any wires with croc clips in one end so i'll have to solder.
Second, does 1k go betweek G and D or G and S ? i dont have any wires with croc clips in one end so i'll have to solder.
Idss is measured with Vgs=0.000mV
You ensure Vgs = 0 by shorting these two leads together. One croc clip shorts the two gate & source leads.
The resistor can be attached to the +ve battery terminal or the -ve battery terminal. Again a croc clip does this.
The third croc clip brings +ve to the drain lead of an Nch jFET. The G+S go to the -ve.
Measure Vdrop of the resistor and measure the Vds of the jFET. These should sum to the battery voltage.
You ensure Vgs = 0 by shorting these two leads together. One croc clip shorts the two gate & source leads.
The resistor can be attached to the +ve battery terminal or the -ve battery terminal. Again a croc clip does this.
The third croc clip brings +ve to the drain lead of an Nch jFET. The G+S go to the -ve.
Measure Vdrop of the resistor and measure the Vds of the jFET. These should sum to the battery voltage.
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