What is a good JFET replacement (higher Vp?) for J113 to operate as a constant current source? the ACP+ circuit requires 10mA current source through a 125ohms resistor.
For <20 mA, the DN25 series is not recommended because of high capacitance. What is the problem with using J113 in the ACP+? If you get a value different than 10 mA, simply adjust R4. Higher values give lower current.
I read it in a Morgan Jones book. In practice, it sounds progressively worse below 15 mA. The LND150 is fine below 5 mA but there is a hole between 5 mA to 20 mA, which is perfectly filled by J113.
I guess my use of the DN2540 CCSs in my 2SK79 preamp was borderline. Two were at 5.5mA and one was at 3.5mA.
I used the DN2540 for its higher voltage capability. The J113 was not a candidate because of that.
I used the DN2540 for its higher voltage capability. The J113 was not a candidate because of that.
J113 has lower noise.
If you need a high voltage CCS, you can use J11x cascoded by a DN2540 or one of those depletion NMos from IXYS.
Patrick
If you need a high voltage CCS, you can use J11x cascoded by a DN2540 or one of those depletion NMos from IXYS.
Patrick
Are you sure that J113 is good choice for 10mA CCS?
Idss (minimum) is 2mA at 15V Vgs.
I would rather use instead of it higher Idss device, as J111 or J310 in cascode cCCS (with any IXTP) as EUVL suggested.
Idss (minimum) is 2mA at 15V Vgs.
I would rather use instead of it higher Idss device, as J111 or J310 in cascode cCCS (with any IXTP) as EUVL suggested.
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what about lm317 low current Version?
don't remember the suffix for the low current version
don't remember the suffix for the low current version
If dynamic range is not critical, a zener diode or just a resistor in series can reduce the voltage J113 sees
You can use the smallest IXYS/Littelfuse 500V and 1000V parts - they have a gate capacitance on the order of 100-150pF, unlike the DN2540N5 that clocks in at about 300pF. The Llittle IXYS parts are expensive these days, though.
The J113 jfet is listed as a switching fet for choppers and integrator reset (Siliconix process NCB), and doesn't make a very good current source, as it has a relatively short channel.. I would use one of the depletion mode mosfets or a ring-of-two current source instead.
I wouldn’t worry about the so-called “intended” use. If that were the case, we would’ve run out of parts a long time ago. If the curves are applicable and the other specs are right, why not use it? It is very convenient to use J113.
Well, yeah, but since it's a short channel device, the current may vary more with Vin - this was my experience with its brother device from the NCB grouping, the PN4393, when I tried to use it as a current source in earlier efforts. Since the J113 is the lowest in the IDSS ranking of the J111-J113 series, it might fare better in that respect. It's certainly one of the last jfets you can buy these days that has leads.....