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jk flip flop, and how to make it toggle

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roelcha

New Member
hi i am quite new to electronics

i have a 5v pulse at about 3000 pulses per minute and i need to halve the speed of this pulse.

i have been told that i can do this with this part
**broken link removed**

i am hoping that someone can tell me which wires go to which terminal on this jk flip flop

i think that i need

wire 1) 5v+ power constant input

wire 2) 5v+ pulse

wire 3) 5v+ pulse output (half the speed of wire 2)

wire 4) 5v- earth (to make the flip flop work)
the following

i have a 5v+ pulse at between 300 and 3000 pulses per min (which needs to be halved)

and i have a constant 5v+ power source.

i also have a 5v- power supply

what else do i need


please help
 

Dean Huster

Well-Known Member
Power (+5v) goes to the Vcc pin (pin 5);
Ground goes to the GND pin (pin 13);
J & K both go to a logical HIGH which is +5v to set up the toggle function (pins 4 & 16 respectively);
Preset and Clear both go to a logical HIGH to disable them (pins 2 & 3 respectively);
The input is to the CLK (pin 1);
Output is at Q (pin 15).

So, when you're done, your "Wire 1" will connect to pins 2, 3, 4, 5 and 16; "Wire 2" connects to pin 1; "Wire 3" connects to pin 15; and "Wire 4" connects to pin 13.

There are two JK flip flops in a 74LS76 and they have common Vcc and GND pins. Otherwise they are fully independent of each other.
 

roelcha

New Member
hi thanks for your help

i have set this up as you specified, but i have a small problem because in order to make it toggle i seem to need a 5v- pulse, and i have a 5v+ pulse

when i use the + pulse i get no response from the multimeter but when i use the - it toggles.

please help me again
 

Boncuk

New Member
Hi Roelcha,

TTL and low power TTL chips normally work with negative logic, while CMOS chips work positive.

Using a HCF4027 you can toggle with a positive going pulse edge.

Here is the schematic.

Q (pin15) goes high on power up, /Q goes low. If you don't want an active output when powering up use /Q (pin14) to toggle.

Boncuk
 

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roelcha

New Member
hi

thanks again

i think that this is the chip that boncuk says that i need

**broken link removed**

if this chip will work please let me know

and if it does please help me work out which wires go to which

wire 1) 5v+ power constant input

wire 2) 5v+ pulse

wire 3) 5v+ pulse output (half the speed of wire 2)

wire 4) 5v- earth (to make the flip flop work)
the following

this is what i have, please help me to find out where each wire should go

thanks in advance
 
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