JFETs are very commonly used in DIY audio designs as buffers, variable resistors for phasers, and gain stages. However, their general unpredictability in manufacturing specifications has caused the broader electronics industry to largely abandon them in favor of MOSFETs which are much more consistent. As a result, over the past several years, most through-hole (TO-92) JFETs have been discontinued.
Most of the JFET models are still available in surface-mount SOT-23 format, but in the DIY pedal scene, we still do most things by hand using through-hole parts. These adapter boards allow you to use surface-mount JFETs in through-hole applications. For the legs, it’s recommended to just solder the clipped leads from other components such as resistors or diodes.
The adapters come in sets of 8 and can be snapped apart by hand, and the tabs removed with pliers. They conform to the D-S-G pinout which is the most common configuration and the style used on most of our effect PCBs.
Please note that many Aion FX designs do have both through-hole and SMD pad options on the board. These adapters are not necessary for those, although they still may be useful if the JFETs need to be specially selected or measured. They have a blank white screenprint on the reverse side that you can use to write the Vgs(off), IDSS, or any other specification, for example if you need to match JFETs for a phaser.