The other diode must be shorted or installed incorrectly.

 

The other diode must be shorted or installed incorrectly.

with just 1 diode connected from the LED indicator to NO wire all works but no low beam LED indicator light on button

 

You need the other diode installed from + LED to the NC, just make sure it's good.

 

You need the other diode installed from + LED to the NC, just make sure it's good.

I will try with another switch too tomorrow

 

You don't need another switch.
I was speaking of making sure the diode is good

 

You don't need another switch.
I was speaking of making sure the diode is good

here is the latest pics I did two new diodes soldered on the switch and the low beam led indicator comes on but the 1 led module blinks on and off the low beam. The high beams work as they should and the led indicator blinks in sequence with them.

Bottom line, one LED module blinks on and off on low beam, and the low beam LED indicator is steady on

 

I just found my error. I forgot the wire spliced off of the NO wire to the breadboard, I was using the LED + indicator on the breadboard positive rail. I feel so dumb, I must have been tired and not thinking straight from all the troubleshooting and testing. I am a happy camper finally! Thill the next adventure LOL Thanks again sir, you are the best!

 

I was using the LED + indicator on the breadboard positive rail. I feel so dumb,

It happens, glad you got it figured out.

 

sghioto, Is it necessary to put a 10K resistor across the gate and source of both mosfets?

 

sghioto, Is it necessary to put a 10K resistor across the gate and source of both mosfets?

That's insurance. You don't want the on/off state of a MOSFET to be "undetermined", or dependent on only the capacitive charge on the gate. Those resistors are called pull-down resistors because in absence of a voltage applied to turn the gate ON, they discharge the gate capacitance and ensure the MOSFET gets turned off in fairly short order.

In many circuits the gate voltage "should" be controlled by ... something, but it's good form to assume that something won't always be either on or off. The resistor makes sure the gate voltage shuts off conduction D-to-S so that a dangerous current cannot flow through the MOSFET in that case.

 

sghioto, Is it necessary to put a 10K resistor across the gate and source of both mosfets?

Not in this case the 100K resistors
R1, R3 and Q1 perform that function.

 

That's insurance. You don't want the on/off state of a MOSFET to be "undetermined", or dependent on only the capacitive charge on the gate. Those resistors are called pull-down resistors because in absence of a voltage applied to turn the gate ON, they discharge the gate capacitance and ensure the MOSFET gets turned off in fairly short order.

In many circuits the gate voltage "should" be controlled by ... something, but it's good form to assume that something won't always be either on or off. The resistor makes sure the gate voltage shuts off conduction D-to-S so that a dangerous current cannot flow through the MOSFET in that case.

Ok I'll do it, thanks

 

Ok I'll do it, thanks

Don't do that see my previous post. That will mess things up as designed.

 

Don't do that see my previous post. That will mess things up as designed.

I'm sorry, I didn't look carefully at your drawing and thought you had included the pull-down resistors that the TS was asking about. I didn't realize he was asking about something not shown. My bad.

 

I didn't realize he was asking about something not shown.

Thank you I appreciate that.

 

Don't do that see my previous post. That will mess things up as designed.

I just built this circuit on a proto board all soldered and all is working,

Then I just saw this post after I had installed the 10k resistors across the gate and the source of the mosfets, and the LED module on Q3 stopped working, but Q2 was still working, so I removed the 10K resistors from Q3 and Q2.

Thank you

 

sghioto,
I know a diode is a check valve that allows current to flow in just one direction, but could you explain what is happening with D1, D2, and D3, in newbie terms so I can wrap my head around it. Thanks

 

Also known as steering diodes or isolation diodes.
I'll start by saying without D2 and D3 the high and low beam LED on Q2 would never come on. Without D1 the low beam on Q2 would not come on as well.
In this application the diodes perform the important function of isolation because you have three interactive circuits.
Similar situation with D4 and D5.
The three diode D1-D3 are only required because of the common negative of the LED lights.
A diode does allow current in only one direction but it also must be biased correctly for that to happen. The voltage on the anode side of the diode must be higher then the cathode side for current to flow. D1 is a prime example. When the switch is in the low beam mode the voltage on the anode of D1 which is connected to pin3 of the 555 is less then 1 volt while the cathode is at appx 10 volts. Because of this D1 is like an open switch which isolates Q2 from the 555 which otherwise would pull the gate of Q2 too low preventing it from turning on in the low beam mode.
The schematics below represent the effective circuits when in the high and low beam modes. Meaning the missing components
are essentially not there.
High beam mode:







Low beam mode:







This is about the best I can explain it.

 

Also known as steering diodes or isolation diodes.
I'll start by saying without D2 and D3 the high and low beam LED on Q2 would never come on. Without D1 the low beam on Q2 would not come on as well.
In this application the diodes perform the important function of isolation because you have three interactive circuits.
Similar situation with D4 and D5.
The three diode D1-D3 are only required because of the common negative of the LED lights.
A diode does allow current in only one direction but it also must be biased correctly for that to happen. The voltage on the anode side of the diode must be higher then the cathode side for current to flow. D1 is a prime example. When the switch is in the low beam mode the voltage on the anode of D1 which is connected to pin3 of the 555 is less then 1 volt while the cathode is at appx 10 volts. Because of this D1 is like an open switch which isolates Q2 from the 555 which otherwise would pull the gate of Q2 too low preventing it from turning on in the low beam mode.
The schematics below represent the effective circuits when in the high and low beam modes. Meaning the missing components
are essentially not there.
High beam mode:
View attachment 294456

Low beam mode:
View attachment 294454

This is about the best I can explain it.

Thank you, just curious, are you an electrical engineer? Self-taught or what?

 

Electronics Technician/Engineer.
Schooling, experience and a lot of self taught.