Dynamic indicator circuit design

Thread Starter

ASB131

Joined Mar 16, 2021
4
Hi all, I'm relatively new to electronics so bare with me. I've given it a shot at designing a circuit which will enable me to have dynamic indicators on my vehicle. I just need someone to confirm with me that the schematic will work correctly, and if any alternations i should be aware of. Basically when the indicators are on id like the LEDS to light up in order, I've done this using op amps but id like someone to confirm with me whether this would work. Thank you, here is my current schematic. Thank you and help would be appreciated.

The VCC is the current indicators power which is 13v.
 

Attachments

Delta prime

Joined Nov 15, 2019
813
Hello there :) welcome to AAC!
The VCC is the current indicators power which is 13v.
Clarification you mean the LEDs is supplied with 13 volts?
Never mind it's your vehicle sorry,
Hi all, I'm relatively new to electronics so bare with me. I've given it a shot at designing a circuit which will enable me to have dynamic indicators on my vehicle
You're a damn good shot!
As is it will fly but a critique is in order and you are about to be bombarded, good show!:)
 

Attachments

AnalogKid

Joined Aug 1, 2013
9,040
As is, it will not fly. There are several problems with the design. But first ...

What is a "dynamic indicator"?
What is the signal or sensor that you are indicating?
How should the indicator indicate? Is it a bar graph type of increasing/decreasing column?

1. There is nothing in the schematic that is variable. In other words, there is no input.

2. Other than GND, there is one Vcc connection that goes to signal inputs. If that Vcc also is the power source for the opamps, it should be shown on at least one opamp symbol.

3. All of the LED strings are connected to a 100K resistor. This means the maximum current available for all LEDs combined is only 90 microamps. That is not enough to produce anything visible, let alone useful.

4. Assuming you fix #3, ... Because all LED strings are connected in parallel to a single current source with a relatively high source impedance, as each LED pair comes on the previous LEDs will get dimmer.

5. The LEDs are connected to the 13 V source through 110K. If you reduce this to get useable brightness, the power dissipated in the current limiting resistors will increase. If you connect the LEDs directly to the 13 V so their brightness do not changd as segments come and go, the power dissipated in the resistors will be over 4 W. poof Even if the LED source voltage is reduced to 6.5 V, the resistor power sill be three times its rating.

6. It looks like the 358's are acting as comparators, with all of the non-inverting inputs tied to 6.5 V. All of the inverting inputs are tied to GND through various resistances, so none of the comparators will turn on their LED circuits.

ak
 
Last edited:

Delta prime

Joined Nov 15, 2019
813
I saw it coming that's why I have this Crystal Ball so now it turns to you pros and cons give us your thoughts what are the LEDs indicating and how dynamic is it¿
 
Last edited:

Delta prime

Joined Nov 15, 2019
813
Because we will show him how!
I mean geez that's why we're here right, rhetorical question.
Remember crystal ball! That's rhetorical as well :p
 
Last edited:

Thread Starter

ASB131

Joined Mar 16, 2021
4
As it will not fly. There are several problems with the design. But first ...

What is a "dynamic indicator"?
What is the signal or sensor that you are indicating?
How should the indicator indicate? Is it a bar graph type of increasing/decreasing column?

1. There is nothing in the schematic that is variable. In other words, there is no input.

2. Other than GND, there is one Vcc connection that goes to signal inputs. If that Vcc also is the power source for the opamps, it should be shown on at least one opamp symbol.

3. All of the LED strings are connected to a 100K resistor. This means the maximum current available for all LEDs combined is only 90 microamps. That is not enough to produce anything visible, let alone useful.

4. Assuming you fix #3, ... Because all LED strings are connected in parallel to a single current source with a relatively high source impedance, as each LED pair comes on the previous LEDs will get dimmer.

5. The LEDs are connected to the 13 V source through 110K. If you reduce this to get useable brightness, the power dissipated in the current limiting resistors will increase. If you connect the LEDs directly to the 13 V so their brightness do not changd as segments come and go, the power dissipated in the resistors will be over 4 W. poof Even if the LED source voltage is reduced to 6.5 V, the resistor power sill be three times its rating.

6. It looks like the 358's are acting as comparators, with all of the non-inverting inputs tied to 6.5 V. All of the inverting inputs are tied to GND through various resistances, so none of the comparators will turn on their LED circuits.

ak
Hi there thank you for the reply. Sorry I didn't make it clear what i meant by dynamic indicator. Here is an example of what i am trying to produce.


Essentially when the indicator is powered on it should charge the capacitor and the op amps should then tell the LEDs to turn on via the transistors. Here is a schematic of what i am trying to produce (the simulation has an artificial switch that discharges the capacitor during the off portion which in real life happens naturally so I don't have to worry about that part.

https://i.gyazo.com/0759cee38a2c0719b869ab6b04200d2b.mp4

I hope this makes sense, if i havnt explained well enough please let me know and i will try harder.
 

click_here

Joined Sep 22, 2020
41
Should the RHS of R16 be connected to VCC, and where VCC is some sort of square wave input?

Also, should the anodes be connected to VCC with better current limiting resistor values?
 

Yaakov

Joined Jan 27, 2019
2,353
Hi all, I'm relatively new to electronics so bare with me. I've given it a shot at designing a circuit which will enable me to have dynamic indicators on my vehicle. I just need someone to confirm with me that the schematic will work correctly, and if any alternations i should be aware of. Basically when the indicators are on id like the LEDS to light up in order, I've done this using op amps but id like someone to confirm with me whether this would work. Thank you, here is my current schematic. Thank you and help would be appreciated.

The VCC is the current indicators power which is 13v.
Chasing LEDs is usually done with a simple decade counter like the 4017 and a 555. It's really a very simple low part count circuit and I am sure you can find many of them online.
 

AnalogKid

Joined Aug 1, 2013
9,040
Chasing LEDs is usually done with a simple decade counter like the 4017 and a 555.
A 4017 turns off each stage as it lights the next one. For a turn signal, you want the successive stages to remain lit. The original system in the Ford Mustang and Mercury Cougar was a synchronous motor turning a shaft with with three offset cams, actuating three microswitches. Today it is done with a microcontroller, but a proper analog would be a shift register.

I like the ramp-and-comparator method, and used it to sequentially power up the auxiliary systems in an ambulance. (Dumping a couple of hundred amps on the alternator all at one time tended to break things.)

ak
 

Yaakov

Joined Jan 27, 2019
2,353
A 4017 turns off each stage as it lights the next one. For a turn signal, you want the successive stages to remain lit. The original system in the Ford Mustang and Mercury Cougar was a synchronous motor turning a shaft with with three offset cams, actuating three microswitches. Today it is done with a microcontroller, but a proper analog would be a shift register.

I like the ramp-and-comparator method, and used it to sequentially power up the auxiliary systems in an ambulance. (Dumping a couple of hundred amps on the alternator all at one time tended to break things.)

ak
Yes, I cut my comment short, I was going to recommend the shift register as a modification to the chasing circuit. Thanks for pointing that out.
 

AnalogKid

Joined Aug 1, 2013
9,040
Now that we know what you are trying to achieve, this will go much better. Thanks for the video.

When I watch the video, I see five stages: right, right+center, right+center+left, all three segments get brighter, everybody off rapidly.

1. Do you have a light device that has 8 sections instead of three?

2. Do you want the last stage of operation to be increasing the brightness of all LEDs, as in the video?

BTW, the "artificial" switch is what turns off all LED rapidly at the end of each cycle by rapidly discharging the timing capacitor. I'm not sure of what you mean by "happens naturally", but without the discharge transistor, the LEDs would ramp down the same way they ramp up, maybe - ***. The sequential systems I've seen do not do this; they are like the video - ramp up slowly, then everybody off all at once. Which way do you want?

Also, neither the animation nor your schematic show how the opamps are powered, either with direct vehicle power or through the turn signal blinker.

*** There are several unknowns regarding the simulation schematic. One of them is the 1.5 Hz oscillator. The high output is around 12-13 V, but the low output is a question. If this is an electromechanical turn signal blinker, then the low state is actually an open circuit. In this case, the only thing available to discharge the ramp capacitor is the transistor switch. Without that switch, the circuit will ramp up on the first half-cycle of the blinker, then sit there with all LEDs on all the time curing successive cycles. OTOH, if the oscillator is an electronic circuit such as a 555, then the low state can sink current. Now, without the transistor switch, the LEDs will sequence off in the reverse order as when they came on, but with the same timing - slow ramp up, slow ramp down.

Details, details ...

ak
 
Last edited:

Audioguru again

Joined Oct 21, 2019
2,847
Be aware that, depending where you live, vehicle lighting is subject to various legal requirements.
I notice that the LEDs light dimly (only 1 pair of LEDs at first) then get brighter as the bar length increases. Then it is too dim at the beginning and the circuit is illegal. But the 20 ohms resistors will probably allow each series pair of LEDs to draw about 430mA, then the total of 9 pairs draw 3.87A and will blind other drivers at night.
 

Thread Starter

ASB131

Joined Mar 16, 2021
4
Now that we know what you are trying to achieve, this will go much better. Thanks for the video.

When I watch the video, I see five stages: right, right+center, right+center+left, all three segments get brighter, everybody off rapidly.

1. Do you have a light device that has 8 sections instead of three?

2. Do you want the last stage of operation to be increasing the brightness of all LEDs, as in the video?

BTW, the "artificial" switch is what turns off all LED rapidly at the end of each cycle by rapidly discharging the timing capacitor. I'm not sure of what you mean by "happens naturally", but without the discharge transistor, the LEDs would ramp down the same way they ramp up, maybe - ***. The sequential systems I've seen do not do this; they are like the video - ramp up slowly, then everybody off all at once. Which way do you want?

Also, neither the animation nor your schematic show how the opamps are powered, either with direct vehicle power or through the turn signal blinker.

*** There are several unknowns regarding the simulation schematic. One of them is the 1.5 Hz oscillator. The high output is around 12-13 V, but the low output is a question. If this is an electromechanical turn signal blinker, then the low state is actually an open circuit. In this case, the only thing available to discharge the ramp capacitor is the transistor switch. Without that switch, the circuit will ramp up on the first half-cycle of the blinker, then sit there with all LEDs on all the time curing successive cycles. OTOH, if the oscillator is an electronic circuit such as a 555, then the low state can sink current. Now, without the transistor switch, the LEDs will sequence off in the reverse order as when they came on, but with the same timing - slow ramp up, slow ramp down.

Details, details ...

ak
Thank you all for your comments ill take away what has been said here and try a redesign of my circuit, this was a starting point from me so i feel like i have more knowledge to have another crack at it and have a more positive result. Next i will try and approach this using a 8 bit shift register, more specifically the 74HC595N register.
Regards
 

AnalogKid

Joined Aug 1, 2013
9,040
Note - I'm not saying a shift register approach is better than an analog approach, just that it is a better digital approach than a Johnson counter for the optical effect you want.

ak
 

ElectricSpidey

Joined Dec 2, 2017
1,529
If you go with a shift register consider the TPIC6B595 it has open collector outputs that can drive LEDs directly and has an enable pin where you could ramp up PWM to create your effect.
 

ElectricSpidey

Joined Dec 2, 2017
1,529
This is only a concept, I don’t really have the time to make sure it will work, and I have some lack of knowledge using the shift register, so the clocking and data may be incorrect.

Basic operation:

The 555 clocks the 4017 and the shift register together.

When any of the 4017s outputs are high other than “8” the 555 runs quicker.

Each 4017 output pin presents a different voltage to the voltage to PWM module.

When the 4017 reaches output “8” it clears the shift register and lifts R1a causing a longer “off” delay, also setting the PWM to “0”.

Again...this is only a CONCEPT block diagram.

ACC_Shift_Register.jpg
 
Top