None of the 4 diodes makes any sense.
The left diodes and the middle 4082 gates have no effect.
The result is the same if you connect the left 4082 gates directly to the 4001 gates.
What are you trying to achieve?
As already mentioned, the CMOS logic inputs in the 4000 series must not "float". A defined logic level is needed.
Without pullup/pulldown this is just "by accident", because without the diodes you don't have reliable, valid voltage levels.Not so - the right-hand diodes make no sense but are making the breadboard version functionally identical to the simulation version.
Not for Goldfish (the cat would soon finish them off) but for something similar I made a £5 (~$7 US) timed light switch recently. Accurate within about 1 second and it tracks the daylight based on the date, latitude and longitude. So it basically turns on at sunset and off at sunrise every day of the year. Timing is from NTP over WiFi.
I appreciate you are using 'bits from the junk box' but it does seem overkill for such a simple task.
Brian.
Why all of the 4082 & diode complexity, when you could do the
same with a 4011 NAND2 (using two of them as inverter so
NAND -> AND)?
The power-up behavior may just want an asymmetric burden
on one of the SR core legs (or, a NOR3 w/ a RC network perhaps;
you could use the "spare" two CD4001 channels to expand one
side).
All unused inputs should be grounded on all CMOS logic unless
they have internal pullups (these, do not).
Hi,
Without pullup/pulldown this is just "by accident", because without the diodes you don't have reliable, valid voltage levels.
Don't rely on the "luck" of some "trial and error", better rely on specifications.
Your "solution" may work with a simulatiin, but this does not mean it wil work with a real circuit.
And even if it works on a real circuit, it does not mean it works with identical devices from the same production batch, different batches, different temperature, different supply voltage, different time....
Klaus
I miss your circuit for this.You who understand hysterisis and comparators well, if I may ask you here - is having a fan turn on at 26ºC (3V) and off at 20ºC (2.936V) exaggerated/too small a window of operation and in practice the comparator will be turning on and off every two minutes?
I miss your circuit for this.
3.000V vs 2.936V:
For an experienced analog circuit developer it should be no problem. For a hobbyist it will be difficult.
Can't you choose a more suitable sensor?
What about a digital sensor and a microcontroller?
Switch ON/OFF timing:
This depends on a lot of things: Temperatures, stored thermal energy, mass flow...
See above. This is only a window of about 65mV. Without correct signal routing, stable references .. the errors may be larger than the window...Why do you say it will be difficult?
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