Roland Space Echo

[samoth]

Hi all,

does by any chance anyone know about the oscillator circuit of the space echo (RE-x01)? I'm particular interested in the transformer. Meaning what are the specs of such a tranformer and are there possible substitutes or humble diy approaches?

Thanks,
thomas

[messager]

i think you will find out in the service manual

RE201 service manual

[unclejed613]

i suppose you're talking about the bias oscillator. bias oscillators are usually ultrasonic (this one is 60khz, but i have seen them as high as 300khz before) and a pretty high voltage output (about 250V p-p being typical) but a very low current (under 1ma) the primary is usually wound for 12V ct (12V center tapped, meaning that the voltage across 1/2 the primary will be 12V) so the turns ratio will be between about 10:1 to 15:1. you coulf DIY one with a small toroid core and some 26GA or 28GA wire for the primary and 40GA wire for the secondary. you will need a couple of layers of insulating tape between the primary and secondary to provide the 500V of isolation needed to keep the secondary from arcing to the primary. teflon plumber's tape is pretty good for this, since teflon has one of the highest breakdown voltage-to-thickness ratios of any insulating material. before winding, put a couple of layers of teflon on the core as well. do not put the secondary down in layers unless you separate each layer with teflon. this keeps the secondary from arcing to itself.

to wind the windings, you should figure out how much wire you will need for each winding, and wind that amount plus about 20% on to a "shuttle". this will make winding a toroid much easier. also figure out how much room will be left through the center of the donut once all the wire is in place, and make the width of the shuttle just a little bit smaller than that. shown below is how the shuttle should be shaped. make it out of a stiff material so it doesn't deform once you begin winding wire on it. the longer the shuttle is, the more wire it will hold.