Auto Printer Switch

[Burnzee]

Hi Guys

Looks like yah got a good thing goin' here!! Thought I would join. So here's my first thread.

For sometime now, I have thought about making a simple automatic printer switch. This is for two computers to share one printer. I'm aware, you can buy one but that's against the grain, rather make one.

Anyway, saw a design somewhere for a manual printer switch using a rotary control. This got my creative juices flowing. Why not replace the rotary switch with CMOS transmission gates or similar? Thought about using CD4052's.

As I see it, the first part of the proposed circuit would detect a high on the appropriate data input, this will tell the circuit which computer wants to print. This then locks out the other computer until print job is complete, using the inhibit control line.

Now the transmission gates switch and the printer does it's thing. Afterwards the circuit resets and waits till next print job.

Simple - Yeah Right!! Got any ideas to help me.

Thanks in advance.

BURNZEE

 

[HarveyH42]

I bought a couple of USB switches, but not really automatic. Works with other things besides printers. Got a four port hub plugged into it, and share an SD card reader, laser printer, and photo printer.

You didn't state what interface your printer uses, but figuring it's USB. Serial is kind of timing and noise sensitive. Might be more hassle, than what you would save on buying. Mine was around $15 shipped, from a deal a day site.

 

[kchriste]

You'd be pretty much out of luck trying to auto switch a USB printer. Manually switching wouldn't be too difficult.
Why not network the two computers and share the printer? (cheapest solution)
Or add a network print server adapter box to the printer if you don't want to always boot the host computer. (Though this can have compatibility issues)
Or buy a printer with built in networking. (the best solution)

 

[Torben]

You'd be pretty much out of luck trying to auto switch a USB printer. Manually switching wouldn't be too difficult.
Why not network the two computers and share the printer? (cheapest solution)
Or add a network print server adapter box to the printer if you don't want to always boot the host computer. (Though this can have compatibility issues)
Or buy a printer with built in networking. (the best solution)

I agree except that I'd say that buying a printer with built-in networking is the best solution only if it solves the problem the best, and if saving money is part of the problem, then it's not the best solution.

I'd go with networking the two computers and sharing the printer (or better yet running a free networking print server on one computer).


Regards,

Torben

 

[shokjok]

The smallest circuit for this uses two 74LS244 buffers ( one for each printer), a 74LS85 magnitude comparator driving a small transistor or buffer to select one of the LS244s, and cabling to connect the signals to the components. You haven't specified the printer types or if they have auto powerdown after prolonged idling.

 

[Burnzee]

Hi Shokjok

Thanks for your reply. Looking into the component data sheets now. Think you might have misunderstood my requirements. What I'm designing is an automatic switch to send data to one printer from either of two computers. NOT from one computer to two printers!! The printer does have auto powerdown but this is no hassle.

However, these type of circuits are backwards compatible so guess your reply still applies. Do you have a circuit for one? Be most interested.

Thanks Again

BURNZEE