NAND Gate circuit with HEF40107B dual 2-input IC

Thread Starter

cevval

Joined Dec 6, 2011
63
Hi everybody.
I am back again.
I try to design a simple circuit using 4093 quad and 2-input IC NAND gate. Since I need only one gate, to simplify the diagram and save space on circuit board, I searched for an 8-pin nand gate IC. I found HEF40107B dual 2-input IC.
I used this one instead of 4093 same way. But it didn't work.
Why?
 

Ian0

Joined Aug 7, 2020
6,660
Hi everybody.
I am back again.
I try to design a simple circuit using 4093 quad and 2-input IC NAND gate. Since I need only one gate, to simplify the diagram and save space on circuit board, I searched for an 8-pin nand gate IC. I found HEF40107B dual 2-input IC.
I used this one instead of 4093 same way. But it didn't work.
Why?
You forgot the pull-up resistor. The 40107 has an open-drain output stage.
For a small device will a push-pull output, look at 74HC1G14, but you would be limited to 5V supplies.
 

Alec_t

Joined Sep 17, 2013
13,224
The 4093 is a Schmitt NAND with hysteresis. The 40107 is not a Schmitt type, so doesn't work as an oscillator in your circuit.
 

MrChips

Joined Oct 2, 2009
27,651
Hence you have two issues.

1) 40107 is open drain. You need a pullup resistor on the output
2) 40107 is not Schmitt trigger inverter.

You can try this dual NAND gate (or NOT gate) oscillator circuit with your 40107. Remember to add the pullup resistors.

1640785898267.png
 

Alec_t

Joined Sep 17, 2013
13,224
Here's a variation which should work, using the two NAND gates plus R1,R2 as a wide-hysteresis Schmitt circuit.
HEF40107-Osc.jpg
The LED plus R4 provide the pull-up for U1b. Tweak Rt,Ct for the pulse timing.
 
Last edited:

Thread Starter

cevval

Joined Dec 6, 2011
63
Here's a variation which should work, using the two NAND gates plus R1,R2 as a wide-hysteresis Schmitt circuit.
View attachment 256327
The LED plus R4 provide the pull-up for U1b. Tweak Rt,Ct for the pulse timing.
I gave up using 40107 IC, because I could not make it work.
Now, I decided to continue with IC 4093 and also try to improve my circuit as such:
Led will be flashing only at darkness like roof top signal lights of high rise buildings. Here below, I attach circuit diagram of my idea.
But at day light led lights without flashing, which I don't want. On the other hand it flashes at dark luckly. How can I overcome the problem to assure the led will be off at day time. Please help.
@Alec_t
 

Attachments

sagor

Joined Mar 10, 2019
786
The 4093 can only source or sink a few mA of current, probably not enough to power the LED. The 40107 can typically sink at least 32mA (or more) at 5V Vdd, enough to allow lighting up any LED.
Your can still use a 4093 but you have to provide a LED driver between the 4093 output and the LED, such as a transistor or small MOSFET
 

Thread Starter

cevval

Joined Dec 6, 2011
63
The 4093 can only source or sink a few mA of current, probably not enough to power the LED. The 40107 can typically sink at least 32mA (or more) at 5V Vdd, enough to allow lighting up any LED.
Your can still use a 4093 but you have to provide a LED driver between the 4093 output and the LED, such as a transistor or small MOSFET
Thanks for your interest on my subject.
Actually led lighting up as flashing at dark time, but it is still lighting at day light time but without flashing. I want it to be off at day light time to save battery life as much as possible.
 

Thread Starter

cevval

Joined Dec 6, 2011
63
Connect the LED to the positive supply instead of the negative.
Thanks.
I try this option soon. But I think it will reverse signal and mark time (easy to change to get short signal time and long mark time again- my preference). But I am not sure that led will be off at day light time. See soon.
 

Ian0

Joined Aug 7, 2020
6,660
The 4093 can only source or sink a few mA of current, probably not enough to power the LED. The 40107 can typically sink at least 32mA (or more) at 5V Vdd, enough to allow lighting up any LED.
Your can still use a 4093 but you have to provide a LED driver between the 4093 output and the LED, such as a transistor or small MOSFET
CMOS always used to be able to light an LED back in the 1980s! Even in the days where you could hardly see an LED unless it had 10mA through it. Now some of them are seriously bright at 1mA
 

AnalogKid

Joined Aug 1, 2013
10,170
I try this option soon. But I think it will reverse signal and mark time
Yes, it will.
(easy to change to get short signal time and long mark time again- my preference).
Yes, by swapping R5 and R6. Or by reversing D1 and D2. Make either change, but not both.
But I am not sure that led will be off at day light time.
The schematic in post #10 has a logic error. As shown by your own notation, there is a logic 0 at pin 8 in the dark condition. To enable flashing, this should be a logic 1. This can be corrected by removing IC1.2 from the circuit, and driving pin 8 with pin 10. This will have no effect on the Schmitt trigger action. Now the LED will flash in the dark condition. To have it off in the light condition, change the LED connection as in post #11.

ak
 

Audioguru again

Joined Oct 21, 2019
5,406
Any old CD4xxx Cmos logic IC can supply plenty of output current (enough to destroy an LED and itself) with a fairly high supply voltage but only 1mA with a 3V supply.

What is a HEF40107 because there is no datasheet online?
 
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