Need help building a circuit for low voltage alarm with bi color LED with flasher

[Pyramid]

The thresholds are 11V / 10V / 9.5V, so post #3.

The 74HC132 is a replacement for a CD4093, but with higher drive capability. Check that the pin out is the same (I don't have a data sheet in front of me).

Find a Piezo beeper that runs from 5V and is self exciting (when you supply 5V, it chirps). The other type requires a squarewave of the frequency you want it to produce to create a chirp.

 

[Audioguru]

The 74HC132 is a high output current replacement for the CD4093 low output current IC. The CD4093 schematic shows a 5V supply but now you changed it to 9.24V to 13.2V so the 74HC132 cannot be used.

What is the function of an LED? To produce light, right? Then why do the Chinese spec's about the very cheap LEDs not say a single word about their brightness??? Are they fakes or factory rejects?

 

[Pyramid]

The opamps and the 74HC132 are still powered from the 5V VCC so it should work. Even at 3mA, most high brightness LEDs will work fine in this circuit.

 

[Audioguru]

The 330 ohm resistors in series with the LEDs limit the 74HC current to about 7.6mA in the 2V red LED. It can be reduced to 100 ohms for 22mA of current. The maximum allowed continuous current from a 74HC IC is 25mA per output but no more than 2 outputs.

 

[Brad Hruska]

The 330 ohm resistors in series with the LEDs limit the 74HC current to about 7.6mA in the 2V red LED. It can be reduced to 100 ohms for 22mA of current. The maximum allowed continuous current from a 74HC IC is 25mA per output but no more than 2 outputs.

The opamps and the 74HC132 are still powered from the 5V VCC so it should work. Even at 3mA, most high brightness LEDs will work fine in this circuit.

Hey guys, Ok I can not get any 74hc132's I can only get the cd4093, so what do I do, will the cd4093 work with the 20ma 8mm led with the schematic? is there anyway to get this brighter if needed?

 

[Pyramid]

I built up the circuit using 5V, a CD4093 and a high brightness (2500 mcd) Red LED. Using a 330Ω resistor swamped the gate and it wouldn't toggle. Increasing the LED resistor to 1K allowed it to operate and it had plenty of brightness.

If you need more brightness, then use a PNP transistor and delete the 2nd 4093 gate (used only as an inverter):



Using the same high brightness LED and a 330Ω resistor, it was almost uncomfortable to look at.

 

[Audioguru]

Digikey has thousands of 74HC132 ICs in stock today from Texas instruments for $.76US each or from Toshiba for $.67US each in through hole DIP packages or all the other surface mount packages. Other suppliers also stock thousands of them.

 

[Brad Hruska]

I built up the circuit using 5V, a CD4093 and a high brightness (2500 mcd) Red LED. Using a 330Ω resistor swamped the gate and it wouldn't toggle. Increasing the LED resistor to 1K allowed it to operate and it had plenty of brightness.

If you need more brightness, then use a PNP transistor and delete the 2nd 4093 gate (used only as an inverter):

View attachment 31769

Using the same high brightness LED and a 330Ω resistor, it was almost uncomfortable to look at.

Hey Pyramid,
I ran into a problem with the led, The LED is different than what you have designed the circuit for. The bicolor led is NPN
The left terminal is negative for green, the center is positive, and the right is negative for red.
Please inform as how to do this.

I have checked for a 8mm Bicolor red/green in PNP format but unable to locate here in Taipei.

 

[Audioguru]

Your bi-color LED is called "common anode", not PNP.

 

[Brad Hruska]

I built up the circuit using 5V, a CD4093 and a high brightness (2500 mcd) Red LED. Using a 330Ω resistor swamped the gate and it wouldn't toggle. Increasing the LED resistor to 1K allowed it to operate and it had plenty of brightness.

If you need more brightness, then use a PNP transistor and delete the 2nd 4093 gate (used only as an inverter):

View attachment 31769

Using the same high brightness LED and a 330Ω resistor, it was almost uncomfortable to look at.

Hey pyramid could you take a look at this post and give me some insight please.

https://www.electronicspoint.com/th...a-momentary-backup-battery-for-bridge.282536/

 

[Brad Hruska]

I just realized you may be able to simplify the circuit by gating the flasher and beeper oscillators directly:
View attachment 31605
The 4093 has 4 gates in one package, so you would only need 1 chip.

Pyramid I have wired up the circuit exactly as is displayed, but it is dead and will not work. I have 4 questions.
1. Please look at your schematic on pin 3, 2, 1 I have voltage after 18k resistor but before the 1k resistor of 4.26v, after the 1k resistor i still have voltage of 4.26 volts going to pin 3 Is this normal not to have a voltage drop after the 1k??

On the schematic you stated that pin 3 should be 3.92v. IS THE SCHEMATIC CORRECT?? or should the connection for pin 2 be where pin 3 is like all the others on the circuit.
I have 3.92 but it is on pin 2, not on pin 3.

Question 1. which way should it be; pin 2 with 3.92 and pin 3 with 4.26 OR is it pin 3 with 3.92 and pin 2 with 4.26v???

I noticed that tl064cn chip has a VCC+ on pin 4 and a vcc- on pin 11. the 4093. The cd4093be has a vcc+ on pin 14, and vcc- on pin 7.
Question 2. do the chips have to be powered up and connected to the power supply and the ground to work??

Question 3. If the chips have to be powered which power supply should be used, the let 1 which is 12v, or leg 3 which is 5v on the 78L05??, For the ground I assume the middle leg of the 78L05 correct?

Please let me know