The ultimate anti-speaker pop circuit

**Rob** · 06-17-2002, 01:26 PM

The other night at 2 am while drunk I came up with the idea for a circuit to turn the amp / speakers on and off, via the computer.

Nothing out of the blue, you say, but here's the cunning part it connects to your LPT and works even if you've got a HD44780 character LCD connected to your printer port.

Here's the link

Rob

edit: might help if I typed the link correctly the first time

**ShinkunoNamida** · 06-17-2002, 02:29 PM

brilliant! If only I wasn't a moron when it comes to making things

Now when you shutdown your computer you don't generally run a command to shut down... how would you execute the second command? If you don't execute it.. the speakers will just stay "on" won't they?

**Rob** · 06-17-2002, 02:44 PM

You can get windows to run programs on shut down, I forget where the option is, or you can use a batch file.

Originally posted by ShinkunoNamida
brilliant! If only I wasn't a moron when it comes to making things

It's just a case off using enough liquid stimulus (beer)

**magnetik** · 06-17-2002, 07:50 PM

u can do alot when fueled by beer..... very nice little circuit...

I can see other uses besides just speaker switching...... maybe an electric antenna? etc ? etc?

if u want someone to bash out some w32 .exe's from visual basic PM me and I will knock some up to include on your page....

**sxpert** · 06-18-2002, 03:48 AM

according to
http://www.doc.ic.ac.uk/~ih/doc/lcd/instruct.html
The MSB is somehow required too.
however, there is one more trick...
the HD44780 LCDs require 3 control signals (see http://www.doc.ic.ac.uk/~ih/doc/lcd/...ple/conn1.html ).
the Parallel port has 4 signals available.
(as explained in http://www.doc.ic.ac.uk/~ih/doc/par/ )
Thus, you can have the best of both worlds...

Sincerely

Amaury

**Rob Withey** · 06-18-2002, 04:27 AM

You can quite happily drive an HD44780 controller with only 4 data lines and a couple of control lines. I do this to keep my wire count down. That gives you loads of spare lines - I use two to drive my aux-in switch on my headunit.

Rob

**phil.45** · 06-18-2002, 04:36 AM

Originally posted by Rob Withey
You can quite happily drive an HD44780 controller with only 4 data lines and a couple of control lines. I do this to keep my wire count down. That gives you loads of spare lines - I use two to drive my aux-in switch on my headunit.

Rob

Wouldnt that only drive a single line? I dont know Im just guessing. Could I do this to drive a 2x16 HD44780? Any chance of the pin outs?

**Rob Withey** · 06-18-2002, 04:42 AM

You need to write a special driver for the HD44780, then use only D4-D7. Just read the data sheet for the HD44780.

Try this: http://www.doc.ic.ac.uk/~ih/doc/lcd/initiali.html

Rob