While i read alot about the popular 74HC595 shift register and its use for multiplexing i can't find anything about the following chips:


Triple 2−Channel Analog Multiplexer/Demultiplexer


Octal D-type flip-flop

The above chips should also be suitable for multiplexing / handling more outputs with less pins, right? I'm not an electronical engineer.. so my knowledge about those ancient chips is limited.

Anyway i'm curious what was the main purpose of this chips and why noone is using them anymore with microcontrollers.

Said that, i have 2x MC14052B & 1x 74HC574. Those parts where taken out from an old sat reciever. And i assume they where there to drive , at least one of them, a 4 digtit 7 segment display. This brings me also to ask if somehow i could use them to drive that display again with an arduino using LESS pins.

Note.: i also have some of the following i2c chips with 8 ports. As i already have a 16x2 display driven by a pcf8574, the combination of the above chips with this one would allow me to drive the diplay with i2c.

PCF8574 ch 8bit 8-bit I/O expander for I 2C-bus

While this appers to be 2 questions, it's just one. If you explain me the use of those chips i'm prolly able to use or not the chips with the 7seg display.At the other side if you explain me how i could hook up the chips with a microcontroller i would understand the usefullness of those chips.

I love IC's, i really want to find something to do with them before throwing them away. I hope you understand me and can help me to undertstand.


1 Answer 1


The MC14052B is basically a means for routing analog signals according to a digital input. It was probably in the satellite reciever for routing audio inputs or outputs. (If you've salvaged these ICs, you should test them thoroughly before using them).

The 74HC574 does exactly what it says in the opening section of its datasheet. On the rising edge of its clock pin, it copies the inputs across to the outputs. The outputs will then be unchanged until the next rising edge. You can optionally turn off the outputs with OE.

If you wire the output of one flop to the input of the next, you can make a shift register just like the 74HC595, although without the handy reset pin.

If stuck on a desert island and required to use these chips to drive a 4x7 segment display, I would:

  • wire the flops up as a shift register as described.
  • wire the LEDs in a matrix configuration, with a particular type of segment as the "row" and the individual blocks as "columns".
  • wire the columns to the 4-way analog switch.
  • wire LED power to the other side of the analog switch.

That then allows me to use two pins to control the analog switch and two pins as clock/data into the shift register. I could then "strobe" through the 4 units, changing the values in the shift register each time. This does require constant CPU attention in order to maintain the strobe frequency.

  • \$\begingroup\$ Nice, thank you... so yeah audio... right... even if i took it out of a AV decive i wasn't totally thinking of that purpose.. right. thank you. Now, as i understand partially what you explain in the hookup process, can you PLEASE show me circuit how too do that? i really don't get it only with words. pls. if you want i draw the chips for you and you edit it? \$\endgroup\$
    – cocco
    Jul 15, 2015 at 16:03
  • \$\begingroup\$ PCF8574 + 74HC574 possible? or do i also need the mc14052b. ah and the 4dig7seg has also a dot. so 8 seg?? \$\endgroup\$
    – cocco
    Jul 15, 2015 at 16:05
  • \$\begingroup\$ they work... i took them out from sockets.. so no soldered parts, no heat. No electrostatical. the reciever worked perfectly ... the satellite is the problem. \$\endgroup\$
    – cocco
    Jul 15, 2015 at 16:16
  • \$\begingroup\$ syntiac.com/img/tens_040623.png \$\endgroup\$
    – cocco
    Jul 15, 2015 at 16:35
  • \$\begingroup\$ basically i2c is to slow, one 74hc574 would be able to control one digit wit 6 pins , to control 4 digits i need to add 4 transistors and so use other 4 pins... total 10 pins including the gnd and +5v. correct? \$\endgroup\$
    – cocco
    Jul 15, 2015 at 16:42

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