Printer Port 256 Relays 16K Dot Matrix -
Using this circuit on Printer Port, one could drive
256 Relays or 16K LEDs as Dot Matrix display. Home
Automation output module of many Relays or Lamps.
It can be used to drive a Large size multiplexed LED
dot matrix display or Latched
Relay-Solenoid-Motor-Lamp Array Drivers.
System - Project Idea
This circuit can be modified for a Static drive
output or a fast changing output like a Waveform
Generator. You can also make it a 16 Bit waveform
generator. The frequency limited to the speed of the
port or a fraction of it, depending on 8bit, 16bit
Now I have Some Explaining to do. Latch the
U7 with a 8 Bit Data to address the device you want
to talk to. So one among the 32 Output Devices can
be Selected by a combination of G1-G2 of U5-U8 and
U7 8 Bits, Split into Two Nibbles for Upper and
Lower 16 Devices. That means 16 * 2 = 32 Devices of
1 Byte each,. 32 * 8 = 256 if my calculations are
correct. Please verify.
256 Relays 16K Dot Matrix - del20021
view circuit click the Link of PNG or PDF, The PNG
Image can be Drag Scrolled with Mouse. .
One of the decoders U5 or U8 decode their respective
nibble and output a Low on Selected device to Latch
Data on the Chosen one (74HCT373). Why HCT ?
Speed is good, low power and CMOS ! and works with
TTL too. It Interfaced well for me on a Card with
Both TTL and CMOS levels, with a Fast uC.
The 74HCT373 outputs are current amplified and
isolated by darlingtons and optoisolators. Both
source and sink examples shown.This circuit
was not tested and documented properly. So there may
be things missing. It is just a Concept design.
Automation by Edward Cheung
Use it, as it is to drive 256 LEDs, Relays or
Outputs, as a 128*128 matrix it can drive 16,384
LEDs dot matrix display in Multiplexed mode.
Modifications over this circuit, can expand it to
any number of outputs, but more outputs means, the
speed of data will reduce. Shown in circuit for only
16 LEDs, Duplicate like that for as many as you
want, upto 32 74HCT373 need to be used. then
you have 32 * 8 outputs.
The design source is here 20021.zip.
Connect to printer port with a good quality shielded