Waldrof Pulse with sync'd oscillators increase the pitch of one oscilator leave the filter wide open with 0 resonance makes a wicked acid sound - sounds nothing like a 303. Sounds like something BT would have used on an album rather than the liberators on a piece of vinyl mind you...but it's a good noise!

Must find the powersupply for the Pulse ... mmm .... still haven't managed to recreate that sound with a soft synth.