At 07:28 PM 1/26/2003 -0500, you wrote: Correction!: I left out the diodes. The secondary can be grounded to earth, but not the primary. Here, an ASCII schematic: metal frame grounded ____ Neutral to Earth | | +----------+ -----|>|---+---------7805|----+----o | | | + |____| | + C||C ### | ### C||C --- | --- C||C | | | 120VAC |||| | | | +----------+||+-----+----+----------+-------+--------+ |||| | | + | | + | C||C === ### | ### === C||C Earth --- _|__ --- GND 240VAC C||C | | | | +----------+ |----|<|---+--------|7905|----+----o |____| LEAVE 120 or 240 unconnected Your new transformer: metal frame grounded ____ Neutral to Earth | | +----------+ -----|>|---+---------7805|----+----o | | | + |____| | + C||C ### | ### C||C --- | --- C||C | | | C||| | | | C||+-----+----+----------+-------+--------+ C||| | | + | | + | C||C === ### | ### === C||C Earth --- _|__ --- GND Hot C||C | | | | +----------+ |----|<|---+--------|7905|----+----o |____| >Maybe I got lucky, heh. Maybe it wasn't a center tap, but rather a screen. This is copper tape or a winding between primary and secondary for shielding purposes. If the wire was green and measures open circuit to all other wires, that's probably what it is. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu