SSR Direct Connect???

[andyhough]

Below was cut/pasted from the wiki. And as it says ask. My questions are this

what is the pinout for a direct connect from the 25pin parallel to two or three SSRs? The next question is; Is this possible? I do not know what an UNL2903s is but I am assuming from this wiki article it makes the link from sourced or positive switched, to synced like the SSRs.

Is it possible to do an 8 or 12 channel direct connect with the regular coop SSRs?

Please enlighten me.

Thanks,
Andy

SSR Direct Attach
Controlled through: Parallel Port
Documentation: Solid State Relays
If you need 12 or fewer channels, you can just buy or build SSRs and connect them to the parallel port on your PC, and use them to turn 110VAC light strings (or just plain lamps) on and off (no dimming). These ssrs must be sourced or positive switched. From time to time there are coop buys of SSR boards,but these are usually sinked, and/or parts, to reduce your expense. You could place a couple ULN2803s and use the coop sinked ssrs. For more information on this come over to the forum and/or ask on the LiveChat.

[dirknerkle]

Below was cut/pasted from the wiki. And as it says ask. My questions are this

what is the pinout for a direct connect from the 25pin parallel to two or three SSRs? The next question is; Is this possible? I do not know what an UNL2903s is but I am assuming from this wiki article it makes the link from sourced or positive switched, to synced like the SSRs.

Is it possible to do an 8 or 12 channel direct connect with the regular coop SSRs?

Please enlighten me.

Thanks,
Andy

SSR Direct Attach
Controlled through: Parallel Port
Documentation: Solid State Relays
If you need 12 or fewer channels, you can just buy or build SSRs and connect them to the parallel port on your PC, and use them to turn 110VAC light strings (or just plain lamps) on and off (no dimming). These ssrs must be sourced or positive switched. From time to time there are coop buys of SSR boards,but these are usually sinked, and/or parts, to reduce your expense. You could place a couple ULN2803s and use the coop sinked ssrs. For more information on this come over to the forum and/or ask on the LiveChat.

The normal ssrs used here at DIYC use pin1 as +voltage and switch the ground. So on a parallel port, pins 18-25 are ground and *usually* pins 2-9 are signal (+v).

The purpose of the uln2803 is three-fold:
1) It inverts the voltage from the port
2) It allows for external power to trigger the ssr in the event the parallel port doesn't have enough oomph to drive a signal a long distance -- sometimes hundreds of feet.
3) It helps (to some degree) isolate the computer from the remote SSRs.

An 8-channel parallel output from a PC can be easily become a decent direct controller for 8 channels by using a single uln2803 and a +5v power supply; port pins 2-9 would connect to pins 1-8 of the uln2803 and power supply gnd to pin 9. Pins 11-18 would be the outputs to the SSRs (the - signal) and +5v from the power supply would go to the SSRs to supply the positive voltage. Pin 10 of the uln2803 is not connected.