Improve Circuit. Unexpected Behavior.

I put together this turn signal / brake simulator to work with another circuit. The goal is to match the cycle of flashes with my vehicle. The circuit flashes and I can adjust it however when i engage/ trip the other push buttons that simulate a left brake pedal press with a right turn signal or visa-versa or a full hazard situation pin (3) on the 555 circuit does not instantly illuminate the LED. Instead it is slow to reach full brightness and delays the relay from engaging. What can I try to make this function as it should?
Note. The green component is not being used.

It would appear that the 555 is free-running so when it goes high is random as compared to when a button is pressed.

It also appears that K1 will not do anything when the brake is applied since it is applying 12V through the turn-signal switch that is already continuously high from the brake signal.

I assume you want the tail-light to blink when both the brake and turn signal are active.
That would require some type of inhibit/logic function to block the brake signal when the turn signal is active.

crutschow said:

That would require some type of inhibit/logic function to block the brake signal when the turn signal is active.

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Other than the 555 free running the remainder of the circuit is manual operated. I simply press a button to create a condition output of the other two leds. For example I will press a button to let the left led flash and hold down another button to make the right led steady. That would produce a scenario of making a left turn while braking. I manipulate the other buttons to produce other conditions that would happen in a vehicle.

The purpose is to route the output of the two leds to the "Third Brake Controller" circuit. The reason is that circuit requires adjustment. That adjustment is to match the flash rate of my vehicle. This circuit allows me to simulate my vehicle from my desk.

ThomsCircuit said:

This circuit allows me to simulate my vehicle from my desk.

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So if it's just for simulation, why is how fast the blink starts a problem?

crutschow said:

Deleted

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Thank you for your help but what does this mean?

crutschow said:

So if it's just for simulation, why is how fast the blink starts a problem?

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it is more evident on slower 1.5 second blinks. I was surprised to find it worked well on faster .5 second blinks

ThomsCircuit said:

it is more evident on slower 1.5 second blinks.

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Turn signal flash rate is set by law, pretty much worldwide from what I can see.

The allowed range is from 60 to 120 flashes per minute, so 1.5 seconds is well out of range.

ThomsCircuit said:

it is more evident on slower 1.5 second blinks. I was surprised to find it worked well on faster .5 second blinks

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I asked why is this a problem for your simulated circuit?

crutschow said:

I asked why is this a problem for your simulated circuit?

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its more of a concern. I am new to this and wanted to know if I wired something incorrectly. Yes faster flash rate works well and for my simulation i will be looking for 60-120 cycles but shouldn't it work the same at any flash rate?

Looking back at the circuit, the 555 and relay 1 section appears to be completely free-running, so the relay should be cycling continuously?

If that is being affected by loads on the contact side or R1, then the only possibilities I can see are either a weak PSU or a wiring fault?

rjenkinsgb said:

If that is being affected by loads on the contact side or R1, then the only possibilities I can see are either a weak PSU or a wiring fault?

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thank you. I will try another power supply. My breadboards have weak spots as well so I'll be replacing them as well.

ThomsCircuit said:

I put together this turn signal / brake simulator to work with another circuit. The goal is to match the cycle of flashes with my vehicle. The circuit flashes and I can adjust it however when i engage/ trip the other push buttons that simulate a left brake pedal press with a right turn signal or visa-versa or a full hazard situation pin (3) on the 555 circuit does not instantly illuminate the LED. Instead it is slow to reach full brightness and delays the relay from engaging. What can I try to make this function as it should?
Note. The green component is not being used.

View attachment 146985

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Shouldn't the "Turn" PB overide its corresponding "Brake" PB?
It doesn't on your schematic.
Or maybe not required for testing the DUT.

eTech said:

Shouldn't the "Turn" PB overide its corresponding "Brake" PB?

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I am completely to blame here for not designing a better schematic.

But it does do what you say it should. This is because I can press one or two buttons at once to produce any scenario.
For example: I can press and hold switches 2 & 3 to simulate a left turn with your foot on the brake. Or I can just press Switch 2 to simulate a left turn without brakes for a lane change. Also just pressing switch 6 to indicates a brake pedal scenario as if to come to a complete stop or to miss hitting a cow or other farm animal. Happens a lot in my area. Then if I get a flat tire I press switch 5 to simulate a hazard condition.

This could have most likely been designed better.
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Been working on the breadboard build. Your version. Its not complete and it is challenging as I'm using one of the negative rails as a trace to connect a number of components.

This is a complex electronic circuit for a simple idea. My 1987 analog trailer tail light interface, an XOR circuit, uses an auto flasher for a clock source. It can be modified to fit inside a handlebar switch block.
I have since removed the two transistors and installed a relay and switch for the REVERSE function.

Sure sounds like a simple state machine in code. Advantage is timing accuracy from
a micro would be so much better than 555 over T & V and component selection. 2-4%.
If this is a one off design than wading thru a pile of electrolytics fine, but if repeatable
production unit 555 not a design choice. And a lot less passive parts, and ability to easily
debounce buttons.

Could use ATTINY85 8 pin dip, or one of its brothers with more pins for more I/O.
Use mBlock to program. Or a Nano board, cheap, timing accuracy xtal controlled,
plenty of I/O.

An example of what can be done with mBlock -


6'th graders using mBlock to program robots. mBlock you drag and drop function blocks, configure,
and mBlock generates the C/C++ Arduino code for you. Note if you learn mBlock there are quite
a few variants of block programming languages and capabilities that operate similar, learning curves
easy, and they bring additional capabilities. Like a talking volt, freq, pulse width......meter -


Regards, Dana.