The new 2016 GuitFET:

The new one sounds great and after some tweaking is in fact better than the original, but has a lot more tone control variation, and a bit more drive. It also has electronic switching between two separate FET overdrive circuits, a mild single FET overdrive and a double FET high OD. This is done with a bistable circuit operated with a momentary foot switch. It also sports a treble boost option which is done on the input FET, giving a much warmer sound than the original GuiFET treble boost, which was done on a regular BJT. Another feature is a bass cut / OD boost option which is done by cutting off the negative feedback to the bass control circuit. This has the effect of turning the bass control into a middy boost to create a very drivy type of overdrive. Warm and funky. As with the original unfortunately I was left with no room for a true bypass switch so this has to be done separately.

What does it sound like? I just recorded the OIL's instrumental 'Wedding Cake Island' with it:

Download a pdf of the schematic here:

After recently gaining further insight into how to maximise the performance of the FETs, I have changed the value of the source resistors from 680 ohms to 1K2 (1,200 ohms). This produces a more even waveform top and bottom and sounds better with less odd harmonics. It aso produces a more stable DC voltage in the FETs which is desirable to prevent the blocking sound when driven into overdrive. Scroll to the bottom of this page to see the test jig I've made: https://www.guitars-of-love.com/GOL_guitFET_new_complete.html

Note that the connections for the LEDs are not included in the schematic. These are facilitated by the toggle switch's spare terminals and knock down resistors to each LED from the DC supply.

NOTE: Initially I had a hum problem with the PS but this has been fixed. It's preferable to use low ESR caps on the raw DC input from the diode bridge. 2 x 3300uF/25V low ESR electrolytic caps to give a better quality 9V DC. Also reccommended is a larger than spec power transformer as this will reduce PS noise as well.

A pdf of the Vero board design for the new one is here:. The power supply and bistable switch are on a separate board; the PS board being half the size of the main board after trimming.