What through hole device can I use instead of a SOT23 format BF862 please?

[Chris Wilson]

What through hole device can I use instead of a SOT23 format BF862 please?


https://www.nxp.com/docs/en/data-sheet/BF862.pdf  shows the specs.

The circuit it would be used in is hopefully attached. Thank you!

[ogden]

What through hole device can I use instead of a SOT23 format BF862 please?


https://www.nxp.com/docs/en/data-sheet/BF862.pdf  shows the specs.

The circuit it would be used in is hopefully attached. Thank you!

It's just LED current limiter. You can use resistor.

[T3sl4co1l]

If the inputs are the voltages shown, just use 1k resistors.  They're literally using them as (8 to 20mA) current limiters.

Ew, a step-up gate drive transformer, and no winding details (core, but not winding).

Ew, ancient fatass transistors too.  Those 1 ohm gate resistors aren't going to do anything.

I've seen Tesla coil circuits better than this, which is saying something...

Ed: ew, and using a 6N136 in phototransistor mode.  Just use a 4N35, except those aren't fast enough. It just gets worse the more I look at it...

Tim

[bson]

You should be able to drop in any N channel JFET with a suitable Ids at Vgs=0.  For example, J110 (10mA @ Vgs=0), J111 (20mA @ Vgs=0), both available in a  TO-92 package.  But it really depends on what LED current you want.  The quiescent current also isn't a hard specification, so we're talking ballpark.  I believe the max LED current for the 6N136 is 25mA?  The J110 probably is a good starting point.

J110, J111 in TO-92:

https://www.mouser.com/ProductDetail/InterFET/J110?qs=sGAEpiMZZMv4z0HnGdrLjo0W1AxRZQdlXPGpjxX7bVahwwoTN%2fTXPg%3d%3d
https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/J111?qs=sGAEpiMZZMv4z0HnGdrLjpo3FY8YkyPv%2ff16NpPbr4w%3d

Be warned, these devices are ESD sensitive.  Always make sure you're grounded when handling discrete JFETs.