Circuit of the switch 12v. led-lighting

kaspiysk113 · Mar 29, 2020

One Bit Switcher

I offer my own version of the circuit of the switch 12v. led-lighting for the kitchen based on the dual trigger of the hc74 chip.
Created with EasyEDA.

Pommie · Mar 29, 2020

That seems like a very complex way to replace a switch.

Mike.

Nigel Goodwin · Mar 30, 2020

Pommie said:
That seems like a very complex way to replace a switch.

Mike.

Yes, and not to mention there's no power to the chip either?.

kaspiysk113 · Mar 30, 2020

Nigel Goodwin said:
Yes, and not to mention there's no power to the chip either?.

sorry, I forgot to draw the hc74 power circuits

perhaps for someone this is a difficult way, it may well be, but the scheme is simple and many will be able to repeat it

rjenkinsgb · Mar 30, 2020

The circuit should work OK.
But: Remember one of the most basic engineering principles - KISS - Keep It Simple, Stupid!

How is that circuit in any way more functional or more advantageous than using the switch to directly control the relay coil - or indeed, control the lamp circuit directly?

As an educational project it is a novel application, but I do not see it to be more than that?

kaspiysk113 · Mar 30, 2020

rjenkinsgb said:
The circuit should work OK.
But: Remember one of the most basic engineering principles - KISS - Keep It Simple, Stupid!

How is that circuit in any way more functional or more advantageous than using the switch to directly control the relay coil - or indeed, control the lamp circuit directly?

As an educational project it is a novel application, but I do not see it to be more than that?

The scheme is assembled by me and works perfectly.
Of course, it is no more functional or profitable than what you mentioned.
This goal was never set.
The goal was to make the light switch controlled by a single button with a return to the original position. The goal was also to make a small and aesthetically pleasing switch.
So, the principle of "KISS", I believe, was taken into account, thank you for reminding me.

kaspiysk113 · Mar 30, 2020

rjenkinsgb said:
As an educational project it is a novel application, but I do not see it to be more than that?

And, of course, the scheme can also be useful for educational purposes.

kaspiysk113 · Mar 30, 2020

Pommie · Mar 30, 2020

I've still no idea what it does as you've never told us. And, I'm not willing to work it out.

Mike.

kaspiysk113 · Mar 30, 2020

Pommie said:
I've still no idea what it does as you've never told us. And, I'm not willing to work it out.

Mike.

everyone understands to the best of their ability, Mike

I believe that for my part, I both showed and told

good luck to you

AnalogKid · Mar 30, 2020

Pommie said:
I've still no idea what it does as you've never told us. And, I'm not willing to work it out.

The circuit converts an SPDT pushbutton switch to alternate-action. U1A is a set-reset flipflop to debounce the switch, and U1B is a toggle flipflop that drives the output stage.

There is a problem with all of the Set and Reset inputs. This would be more apparent if you drew a schematic instead of a wiring diagram. A correct schematic has separate symbols for each flipflop with the inputs and outputs arranged in a traditional manner, not the physical package. This makes its possible for any experienced viewer to see the intent of the design. Redraw the schematic and you will see the problem. Yes, the circuit works, but not by design.

See figure 3 of this datasheet for the correct schematic symbols.

https://assets.nexperia.com/documents/data-sheet/74HC_HCT74.pdf

ak

ps. Ground symbols never point any direction but down. Antennae and power symbols point up; grounds point downward, always.

Pommie · Mar 30, 2020

Ahhh, so it replaces a push on/push off switch.

Mike.

kaspiysk113 · Mar 30, 2020

AnalogKid said:
The circuit converts an SPDT pushbutton switch to alternate-action. U1A is a set-reset flipflop to debounce the switch, and U1B is a toggle flipflop that drives the output stage.

There is a problem with all of the Set and Reset inputs. This would be more apparent if you drew a schematic instead of a wiring diagram. A correct schematic has separate symbols for each flipflop with the inputs and outputs arranged in a traditional manner, not the physical package. This makes its possible for any experienced viewer to see the intent of the design. Redraw the schematic and you will see the problem. Yes, the circuit works, but not by design.

See figure 3 of this datasheet for the correct schematic symbols.

https://assets.nexperia.com/documents/data-sheet/74HC_HCT74.pdf

ak

ps. Ground symbols never point any direction but down. Antennae and power symbols point up; grounds point downward, always.

Thank you for your comments about the symbols in the diagram, I will keep this in mind in the future.
I have a scheme based on separate function blocks, but I don't see any problems with the “set” and “reset”inputs on it.
What exactly do you mean?

kaspiysk113 · Mar 30, 2020

This same chip was previously used by me to repair the DGT Easy chess clock.
This watch failed to switch time, and the crossbar was not held clearly in one of the positions.
The problem was solved by using the built-in R#/S# triggers in hc74.
If it is interesting, I can publish it on this forum.

AnalogKid · Mar 30, 2020

kaspiysk113 said:
What exactly do you mean?

I think you will see it if you redraw the schematic.

ak

kaspiysk113 · Mar 30, 2020

AnalogKid said:
I think you will see it if you redraw the schematic.

ak

I've redrawn it on a piece of paper, but I don't see the problem you're talking about.

kaspiysk113 · Mar 30, 2020

Scheme

AnalogKid · Mar 30, 2020

kaspiysk113 said:
I've redrawn it on a piece of paper, but I don't see the problem you're talking about.

Trace the four Set and Reset branches in both images, and you will see that they are not the same. The #17 image is correct.

ak

ChrisP58 · Mar 30, 2020

Unless you've already got +5V elsewhere in the system, I'd suggest changing the 74hc74 to a CD4013B flip-flop. The CD4000 series can run on 12 volts, so you wouldn't need a separate 5 Volt regulator. Be aware though, that the logic state of the S and R inputs are different between the hc74 and the 4013. Also the pinouts are different.

Also, I would eliminate the relay by using a mosfet to drive the LEDs.

kaspiysk113 · Mar 30, 2020

ChrisP58 said:
Unless you've already got +5V elsewhere in the system, I'd suggest changing the 74hc74 to a CD4013B flip-flop. The CD4000 series can run on 12 volts, so you wouldn't need a separate 5 Volt regulator. Be aware though, that the logic state of the S and R inputs are different between the hc74 and the 4013. Also the pinouts are different.

Also, I would eliminate the relay by using a mosfet to drive the LEDs.

Thank’s Cris !
these are great notes on the circuit, but it's just that I came from the chips I have, so I used hc74
and the relay is also needed as a sound sounder, I was interested in its click when switching

Circuit of the switch 12v. led-lighting

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