
Jim writes – “In 1983 it ruled the world. By 1993, it was buried in scorn, the victim of cheap knockoffs. But FM synthesis has a sparkly magic that today is stronger than ever, thanks to powerful new software instruments. Jim Aikin explores the top four FM synths and explains how FM can make your music shine.” Thanks Tim! – Link.
while that circuit I’m sure works just fine, I recommend these changes.
first of all, please use an optoisolator to protect your parallel port – it’s very cheap insurance against a very expensive repair … the parallel port is a logic interface, it is not designed to source power to transistors in the manner depicted.
second, depending on the size of the relays, you might need darlington transistors to latch them. alternately, look into “logic level” N-MOSFETs… these use voltage rather than current to do their switching, and are capable of switching huge loads with 5 volts and nanoamps of current.
while that circuit probably works fine, I recommend these changes.
first of all, please use an optoisolator to protect your parallel port – it’s very cheap insurance against a very expensive repair … the parallel port is a logic interface, it is not designed to source power to transistors in the manner depicted.
second, depending on the size of the relays, you might need darlington transistors to latch them. alternately, look into “logic level” N-MOSFETs… these use voltage rather than current to do their switching, and are capable of switching huge loads with 5 volts and nanoamps of current.
while that circuit probably works fine, I recommend these changes.
first of all, please use an optoisolator to protect your parallel port – it’s very cheap insurance against a very expensive repair … the parallel port is a logic interface, it is not designed to source power to transistors in the manner depicted.
second, depending on the size of the relays, you might need darlington transistors to latch them. alternately, look into “logic level” N-MOSFETs… these use voltage rather than current to do their switching, and are capable of switching huge loads with 5 volts and nanoamps of current.
I’m sorry, I’m not too skilled at electronics. In what way does the diode across the relay protect the relay?