[catman]

G'day all, here is the 'circuit'. You might require a series capacitor on the output and also a series capacitor on the gate input of the second FET (1uf MKT).

I used a 1 uf MKT capacitor on the input to the detector but a smaller value might be better, so experiment if you wish! Regards, Felix (vk4fuq) aka catman.

Addition 040315. I've determined that a .1 uf capacitor is pretty well ideal as the value for the 'input' capacitor to the diode voltage doubler detector. I used an MKT capacitor. Regards, Felix (vk4fuq).

Addition: another circuit modification. The 27 k load resistor should be changed to 100 k. This increases the output level considerably without compromising any aspect of normal operation.