I am not a technician, so this may be a simple question for you. I have some L.E.D Christmas lights that are wired with some color in opposite polarity. I'm trying to build a circuit that will switch the polarity in random sequence. I used to install auto electronics, so I know how to do this using relays, but L.E.Ds lack the load to trigger relays, so I'm trying to do it with transistors. I have been unable to locate a schematic for such a circuit. Any leads would be appreciated.

 

Hi

How many LED's light for each polarity?
How long should each LED string be lighted? sec? minutes?
LED spec?
What is LED supply voltage?

 

For your Christmas lights, using a 5V power supply R2 would probably best be 330 ohms to 470 ohms. Q1 could be a 2N222, PN2222, etc.

With transistors, reversing polarity is often done with a full bridge configuration:

Here, the LEDs would go where the black circuit (probably indicating a motor) is shown. Series resistors would be needed to limit current to the LEDs. Important note: Each input needs to be driven to either or +5V otherwise the the transistors in a leg will both be on and could quite likely destroy each other, so do not let the inputs float freely.

In order for an LED to light the two inputs must be in opposite states -one to +5V the other to ground.

You wrote:
"...but L.E.Ds lack the load to trigger relays, so I'm trying to do it with transistors."

Do you intend to use LEDs to trigger relays? I am having trouble picturing how you would do that, and thus am not able to understand that problem.

 

View attachment 264566
For your Christmas lights, using a 5V power supply R2 would probably best be 330 ohms to 470 ohms. Q1 could be a 2N222, PN2222, etc.

With transistors, reversing polarity is often done with a full bridge configuration:
View attachment 264567
Here, the LEDs would go where the black circuit (probably indicating a motor) is shown. Series resistors would be needed to limit current to the LEDs. Important note: Each input needs to be driven to either or +5V otherwise the the transistors in a leg will both be on and could quite likely destroy each other, so do not let the inputs float freely.

In order for an LED to light the two inputs must be in opposite states -one to +5V the other to ground.

You wrote:
"...but L.E.Ds lack the load to trigger relays, so I'm trying to do it with transistors."

Do you intend to use LEDs to trigger relays? I am having trouble picturing how you would do that, and thus am not able to understand that problem.

No, an L.E.D doesn't draw enough current to trip a relay, so I'm looking for another way to flip-flop the polarity of the input to the string of L.E.Ds. In automotive applications, I'd use a flasher from the blinker system to to cause the relays to turn on and off, switching the polarity. But since I'm not a techie, I don't know how to do this electronically.

 

No, an L.E.D doesn't draw enough current to trip a relay, so I'm looking for another way to flip-flop the polarity of the input to the string of L.E.Ds. In automotive applications, I'd use a flasher from the blinker system to to cause the relays to turn on and off, switching the polarity. But since I'm not a techie, I don't know how to do this electronically.

The string of L.E.Ds run on a single AA battery of 1.5 volts. Although I've powered the string with 9 volt batteries and had none blow out. The system has solar rechargers, so I'm guessing that's why such a low current is used.

 

I'm trying to build a circuit that will switch the polarity in random sequence.

What do you mean by "random"?

In automotive applications, I'd use a flasher from the blinker system to to cause the relays to turn on and off, switching the polarity.

Certainly I would not consider an automotive flasher random.

 

What do you mean by "random"?
Certainly I would not consider an automotive flasher random.

True, I'm not very concerned with any set pattern. I just don't want it to to change so fast that it looks like something off the Vegas Strip.

 

No, an L.E.D doesn't draw enough current to trip a relay, so I'm looking for another way to flip-flop the polarity of the input to the string of L.E.Ds. In automotive applications, I'd use a flasher from the blinker system to to cause the relays to turn on and off, switching the polarity. But since I'm not a techie, I don't know how to do this electronically.

Let’s pretend for a moment that the LEDs draw enough current to flip a relay. Could you draw a wiring diagram to show how you would use a relay?

Even though we know it won’t work, the drawing will explain to us what you’re thinking.

 

A relay is triggered by the coil. It has nothing to do with the load, i.e. the LEDs.

Bob

 

random llinks
https://nationalmaglab.org/images/n...summerschool/2016/physics_of_noise_kowitt.pdf
http://www.industrial-electronics.com/measurement-testing-com/aole_16.html
https://www.maximintegrated.com/en/design/technical-documents/tutorials/5/5664.html
https://www.renesas.com/us/en/document/ppt/understanding-noise-signal-chain
http://www.toon-llc.com/support/obng_en.html
requires apx.1M amplification to get hands on the white noise to be able to use it for RND(white)

 

I am not a technician, so this may be a simple question for you. I have some L.E.D Christmas lights that are wired with some color in opposite polarity. I'm trying to build a circuit that will switch the polarity in random sequence. I used to install auto electronics, so I know how to do this using relays, but L.E.Ds lack the load to trigger relays, so I'm trying to do it with transistors. I have been unable to locate a schematic for such a circuit. Any leads would be appreciated.

“but L.E.Ds lack the load to trigger relays,”

That statement is very confusing to everyone trying to help.

Can you show us how you would’ve wired the LEDs if the relay circuit worked?

That way we can more easily understand what you’re trying to do, and convert it to a transistorized version of the circuit.

 

“but L.E.Ds lack the load to trigger relays,”

That statement is very confusing to everyone trying to help.

Can you show us how you would’ve wired the LEDs if the relay circuit worked?

That way we can more easily understand what you’re trying to do, and convert it to a transistorized version of the circuit.

Word of the day - Transistorized

 

L.E.Ds lack the load to trigger relays,

actually the automotive relays - namely - the ones with the 377Ω coil DC resistance actuate at 20mA (7.6V) and disconnect at 7mA (2.7V) . . . if you put two strings of \(I_{FW}=20mA\) leds in parallel you have enough margin to set the relay coil in series -- if that is what was meant by the "lack of load (?range)"
. . .
however using relays is not that good idea - both - because of the inductance and the limited lifespan switching cycles
the DC SCR-s may do the job aswell
https://www.vishay.com/docs/84724/vo1400aeftr.pdf (from https://www.vishay.com/solid-state-relays/ )
https://www.micro-semiconductor.fi/datasheet/ef-H11C13S.pdf
https://my.centralsemi.com/datasheets/2N5060_SERIES.PDF

 

Let’s pretend for a moment that the LEDs draw enough current to flip a relay. Could you draw a wiring diagram to show how you would use a relay?

Even though we know it won’t work, the drawing will explain to us what you’re thinking.

I misspoke, an L.E.D doesn't draw enough to activate a flash can, which I used to use in conjunction with two relays, to cause a blinking circuit reversing the polarity of one half. An incandescent bulb uses resistance to create light, so the heavier load will create enough draw to trigger the relays.

 

I misspoke, an L.E.D doesn't draw enough to activate a flash can, which I used to use in conjunction with two relays, to cause a blinking circuit reversing the polarity of one half. An incandescent bulb uses resistance to create light, so the heavier load will create enough draw to trigger the relays.

And I still need you to provide a wiring diagram. Schematics (wiring diagrams) are the language of electronics. Plus, what is a flash can?

We could guess, but all that would do is generate many more useless posts.

 

a flash can?

? perhaps https://premierautotrade.com.au/news/flasher-cans.php

1. ? How many LED-s in a string
2. ? their current rating or TYPE
3. ? the supply voltage for the LED-s string
4. ?? are the LED-s at reverse pairs ((? different color/TYPE ones))) in a string

 

And I still need you to provide a wiring diagram. Schematics (wiring diagrams) are the language of electronics. Plus, what is a flash can?

We could guess, but all that would do is generate many more useless posts.

A flash can is what made old style car blinkers blink.

 

A flash can is what made old style car blinkers blink.

I think you are confused, but could you point us to a website or any other reference that uses "flash can" in this way?

I think a "flash can" is something entirely different.

 

The string of L.E.Ds run on a single AA battery of 1.5 volts. Although I've powered the string with 9 volt batteries and had none blow out. The system has solar rechargers, so I'm guessing that's why such a low current is used.

I think it is clear that you wanted to use a turn indicator blinker for a car to flash your lights but the LEDs do not provide enough of a load for the blinker to .... blink. So you need another kind of blinker. That is easy enough.

Questions remaining are about the LEDs you want to blink and the available voltages.

1.5 volts is fine for incandescent light bulbs that are designed for that use but not really enough for most active electronic circuits. Do you have access to a higher voltage?

How do you want the LEDs arranged, it seems like you want to have two strings which flash alternatively.

If you want two strings, what voltage is required for each string. Can we assume that these are small LEDs such as those used as indicator lights? (This has to do with the amount of current that will be required)

 

I think it is clear that you wanted to use a turn indicator blinker for a car to flash your lights but the LEDs do not provide enough of a load for the blinker to .... blink. So you need another kind of blinker. That is easy enough.

Questions remaining are about the LEDs you want to blink and the available voltages.

1.5 volts is fine for incandescent light bulbs that are designed for that use but not really enough for most active electronic circuits. Do you have access to a higher voltage?

How do you want the LEDs arranged, it seems like you want to have two strings which flash alternatively.

If you want two strings, what voltage is required for each string. Can we assume that these are small LEDs such as those used as indicator lights? (This has to do with the amount of current that will be required)

The strings came wired with opposing polarity. I don't want to use a flash can, I was just stating that was the only way I knew, of how to reverse the polarity of a circuit, from my experience doing automotive work. I have heard that using transistors will do a similar operation, but I have been unable to find any schematics for that type of circuit. There are many types of transistors, and I don't know enough to discern what type I need. The lights came in a package that would accept two double A batteries, but only used one.