[HELP] overdrive pedal squeels like a high pitched synth

[ulysses]

hey guys

i made a hotcake clone and when i turn the drive right up it squeels like crazy. if i plug in a cable to the in-jack without plugging in the guitar it makes a sound like a high pitched synth-like sound. when i plug the cable into the guitar it stops squeeling. Is it likely that it will be the layout? (i designed the pcb myself). i have never had this problem before with other overdrive pedals with which i designed the pcb.

thanks for your help guys
ulysses

[rockgardenlove]

I had an issue just today when my power supply was causing a bassy synth type sound...maybe thats it.