Hi all. I’m looking for some assistance. I am using 2 4-pin Hall effect sensors on a 6v to 20v DC system that currently switches from one color (blue) LED on the North Pole passing over to another color (yellow) LED after the South Pole passes over (And back and forth). LEDs are held constantly on unless the opposing pole passes over. I’d like to add a third color (red) LED to come on when the south pole is used to change the color from blue to yellow, but only for 1 minute, before finally changing to yellow. I can’t for the life of me figure out how to do this (or if it is even possible outside of an IC). Can someone assist with this if it’s even possible? Happy to answer any questions. Trying to keep the circuit as small as possible. Thanks!!

 

It seems like you need more sensor input! AND the simple scheme is to use some small processor module and do the logic in code. Modifying code is simpler than adjusting a hardware design. BUT it does require a detailed statement of the desired results.
Stating the requirements accurately and with sufficient detail is often a real challenge. That has been true in the engineering profession for a long time.

 

Hi cornb,
Welcome to AAC.
Do you have a circuit diagram you could post?
E

 

I’d like to add a third color (red) LED to come on when the south pole is used to change the color from blue to yellow, but only for 1 minute, before finally changing to yellow.

Couple of ideas if the 4 pin hall sensor is similar to an AH477A.
IC1 provides the 1 minute timer requested.
When DOB is Low LED1 is ON and no power is applied to IC1
When a South pole crosses the hall sensor DO goes Low, DOB goes High and starts the timer.
Pin3 of the 555 goes Low illuminating LED2.
When the 1 minute time expires pin3 goes High illuminating LED3 and turning OFF LED2.
When the North pole crosses the hall sensor DOB goes Low resetting the timer and shutting OFF LED3.
As Eric asked in post #3, can you post your current schematic?

Second version using two transistor

 

Couple of ideas if the 4 pin hall sensor is similar to an AH477A.
IC1 provides the 1 minute timer requested.
When DOB is Low LED1 is ON and no power is applied to IC1
When a South pole crosses the hall sensor DO goes Low, DOB goes High and starts the timer.
Pin3 of the 555 goes Low illuminating LED2.
When the 1 minute time expires pin3 goes High illuminating LED3 and turning OFF LED2.
When the North pole crosses the hall sensor DOB goes Low resetting the timer and shutting OFF LED3.
As Eric asked in post #3, can you post your current schematic?
View attachment 361606
Second version using two transistor
View attachment 361612

Soooo sorry for my delay on this. I have been absolutely swamped with everything possible. if it isn't one thing breaking or pulling me away... it is another. Here is the schematic I currently have. It's very very simple.



Notice that 3 on one sensor and 2 on the other are not connected. This allows me to have steady on with one of the two colors, depending upon which pole of the magnet crosses over.

 

Soooo sorry for my delay on this. I have been absolutely swamped with everything possible. if it isn't one thing breaking or pulling me away... it is another. Here is the schematic I currently have. It's very very simple.

View attachment 362742

Notice that 3 on one sensor and 2 on the other are not connected. This allows me to have steady on with one of the two colors, depending upon which pole of the magnet crosses over.

let me repost so it isn't so clustered.

 

First thing, I don't see the need for two sensors.
In your setup there is only one magnet and the two sensors are right next to each other, correct?
My circuit in post #4 will need a redesign as the AH477 is not the same as a AH276Z4. More later.

 

here is a picture of the functioning sensor - this may help to make more sense of what I was doing.

Lead wires on the right went to the current two LEDs (or single LED that is dual color if desired) + power and ground.

 

here is a picture of the functioning sensor - this may help to make more sense of what I was doing.

Lead wires on the right went to the current two LEDs (or single LED that is dual color if desired) + power and ground.

Still only need one sensor.
Will post a circuit soon.

 

All three LEDs controlled by one AH276 and the 1 minute timer IC1.
When LED1 is on DOB is Low, inhibiting the timer IC1.
When DOB turns OFF, power is applied to IC1, DO is Low and normally would turn ON LED3.
However, when the timer is activated pin7 of IC1 goes Low turning ON LED2 and bypassing LED3 via diode D1.
After 1 minute pin7 is open turning OFF LED2 and allowing LED3 to come ON as requested.
Operation verified on breadboard.

 

All three LEDs controlled by one AH276 and the 1 minute timer IC1.
When LED1 is on DOB is Low, inhibiting the timer IC1.
When DOB turns OFF, power is applied to IC1, DO is Low and normally would turn ON LED3.
However, when the timer is activated pin7 of IC1 goes Low turning ON LED2 and bypassing LED3 via diode D1.
After 1 minute pin7 is open turning OFF LED2 and allowing LED3 to come ON as requested.
Operation verified on breadboard.

View attachment 362778

OMG - you are amazing! I appreciate it so much!! Thank you - now time to order these components and test it out.

 

I have another circuit to post in a few minutes.

 

All three LEDs controlled by one AH276 and the 1 minute timer IC1.
When LED1 is on DOB is Low, inhibiting the timer IC1.
When DOB turns OFF, power is applied to IC1, DO is Low and normally would turn ON LED3.
However, when the timer is activated pin7 of IC1 goes Low turning ON LED2 and bypassing LED3 via diode D1.
After 1 minute pin7 is open turning OFF LED2 and allowing LED3 to come ON as requested.
Operation verified on breadboard.

View attachment 362778

Would an LMC555CN/NOPB work? And for the AH276 - would it be best to use an -AG1, BG1, or CG1? Thanks!!

 

I have another circuit to post in a few minutes.

Any LMC555 type is fine.
The AH276-BG1 or AG1. The CG1 is obsolete.
Version #2 using transistors, verified on a breadboard.

 

Any LMC555 type is fine.
The AH276-BG1 or AG1. The CG1 is obsolete.
Version #2 using transistors, verified on a breadboard.
View attachment 362816

I like this one better. I tried to pull this off with transistors, but I couldn't get it to work right at all. I was missing the 1N4148 which I didn't know about. Let me give this a try (give me a couple of days) to see if this will fit my application. I completely and totally appreciate your help on this! Thank you so much!!!!!

 

Any LMC555 type is fine.
The AH276-BG1 or AG1. The CG1 is obsolete.
Version #2 using transistors, verified on a breadboard.
View attachment 362816

just so i set this all up correctly, would it be too much to ask for a photo of your breadboard setup - i don't want to make a mistake and have to ask a really silly question - thank you!!

 

Sure.
Do you have the correct components needed?

 

Sure.
Do you have the correct components needed?

yes, or I have them on order as of today.

 

would it be too much to ask for a photo of your breadboard setup

 

Hey quick question on this. I decided to go ahead and make a chip to run this system. Can you double check that I have everything setup on the PCB correctly? CN1 is the incoming from the hall sensor. CN2 goes to the LEDs.

Thanks in advance!!