How to Turn On LED with Audio ? - simple circuit

[Whoops]

Here's a sketch of how you might do it with a 555:

View attachment 124371

For a 10s time you'll need a CMOS one, TLC555 or TS555 (https://www.st.com/resource/en/datasheet/ts555.pdf).

Thank you so much for the schematic.
So the circuit you drew uses the TLC555 so is the 10s time already included in this circuit? or do I need to add more circuitry?

Thanks

 

[MidnightArrakis]

I would just need that the LED would stay On for little longer after the signal is detected, instead of turning off right away when the signal is not present.

Maybe this circuit can be modified for that,

>> The main key item about the circuit "Kags" provided you is this: -- After the transient has gone away, it takes time for C1 to discharge, so the LED remains on for long enough for you to see it.

>> Like you, I cannot design circuits either, but I can certainly "build the heck out of them"!!! In this case, I am guessing that the value of -- C1 -- would need to be calculated so its discharge rate is such that the LED stays on for the duration of the 10-seconds that you require. I'm sure that someone on here can easily do that for you.

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[MidnightArrakis]

Hi friends,

I need to build a simple circuit where Audio tuns on a LED,
I could do it with Arduino, but probably it's possible to do this with a much simple analog circuit than to use Arduino.

The goal would be, when there's audio in (Line Level) at the circuit input, the LED turns on, stays On for a 10 seconds, or Blinks (On and Off) for 10 seconds.

Is there anyone that could help me on this?

Thank you so much

WHOOPS -- Take a look at THIS!!! You get 10 timer-circuits for $1.38 (plus shipping):

TZT 10Pcs Multifunction Delay Trigger Timing Chip Module Timer IC Timing 2s - 1000h



https://www.aliexpress.us/item/3256805110149139.html?spm=a2g0o.productlist.main.83.18dd19fdRBcyB3&algo_pvid=7fc9621f-fe6c-4ca3-af33-818a489ddb16&algo_exp_id=7fc9621f-fe6c-4ca3-af33-818a489ddb16-41&pdp_npi=4@dis!USD!1.38!1.38!!!1.38!1.38!@2101ef5e17102214139364963efd5a!12000037070381284!sea!US!3239845106!&curPageLogUid=Zjip1V8aAxiR&utparam-url=scene:search|query_from:










Hope this helps out!!!

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[Voyager10]

Thank you so much for the schematic.
So the circuit you drew uses the TLC555 so is the 10s time already included in this circuit? or do I need to add more circuitry?

Thanks

The 10s time is set by the 2.2M resistor and 4.7uF capacitor in the circuit. You don't need to add any other components.

I've recommended a CMOS version of the 555 (TLC555, LMC555, TS555, there are several) because the original NE555 isn't so good with high value timing resistors; 10s is at the top end of its range. Also the power consumption is much lower, in case you want to run it from a battery.

 

[MidnightArrakis]

That's totally fine, the LED just needs to stay on for a little bit after the audio starts, it doesn't matter if its 10 seconds after the audio ends or 10 seconds when the audio starts.
Both work well, actually I was thinking about 10 seconds after the start of the audio (or at the start)

>> Whoops: It was 2:00 AM here when I posted the information about the timing chip in Post #23 and I was mentally fading fast at that time. What I also meant to include as a comment was.....all that this timing chip needs is some type of buffered audio circuit to feed its "Trigger Input" and then all you need is a resistor value to program its "ON" time to be 10-seconds. As you can already see in the various included schematics, there is an LED to indicate when the chip is "ON".

I hope that this helps "better"!!!

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[MidnightArrakis]

The 10s time is set by the 2.2M resistor and 4.7uF capacitor in the circuit. You don't need to add any other components.

I've recommended a CMOS version of the 555 (TLC555, LMC555, TS555, there are several) because the original NE555 isn't so good with high value timing resistors; 10s is at the top end of its range. Also the power consumption is much lower, in case you want to run it from a battery.

Like THIS???.....




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[MisterCMRR]

Here's a simple "napkin design" off the top of my head. I can't imagine it getting any simpler. As Einstein said, "Everything should be as simple as possible, but no simpler." The critical part here is Q1, a very low threshold N-channel MOSFET. Parts like the TNO702, TNO604, and ZVNL110 are great choices because of their typical +1 V gate threshold spec. Spec "Vth" is the gate voltage required for turn-on of the channel. This sets the minimum peak audio level required at the input. With a 1 V threshold, the LED will turn on around +1.6 V peak input (roughly correspond to a +3 dBu sine wave). There may be lots of other suitable parts, but those with higher Vth will require more input level. All diodes are general purpose types like 1N914 or 1N4448. C2 must be a plastic film type for very low leakage current (electrolytics of any kind or most ceramic types are too leaky for this). R3 and C2 set the time the LED remains on after audio goes below threshold level. R4 is calculated for about 2 mA in the LED, fine for high-efficiency LEDs - and also keeps battery drain low. D1 keeps the input signal from driving the gate too high and D2, along with C2 and R3 form a peak rectifier. R1 is to minimize any distortion that might be added to the monitored line. I figured 9V batteries are everywhere guitar players and stomp boxes are, so chose that as power. Obviously, you can substitute or adapt design for other voltage but wouldn't recommend anything lower than about 5 V.

 

[MidnightArrakis]

Here's a simple "napkin design" off the top of my head. I can't imagine it getting any simpler. As Einstein said, "Everything should be as simple as possible, but no simpler." The critical part here is Q1, a very low threshold N-channel MOSFET. Parts like the TNO702, TNO604, and ZVNL110 are great choices because of their typical +1 V gate threshold spec. Spec "Vth" is the gate voltage required for turn-on of the channel. This sets the minimum peak audio level required at the input. With a 1 V threshold, the LED will turn on around +1.6 V peak input (roughly correspond to a +3 dBu sine wave). There may be lots of other suitable parts, but those with higher Vth will require more input level. All diodes are general purpose types like 1N914 or 1N4448. C2 must be a plastic film type for very low leakage current (electrolytics of any kind or most ceramic types are too leaky for this). R3 and C2 set the time the LED remains on after audio goes below threshold level. R4 is calculated for about 2 mA in the LED, fine for high-efficiency LEDs - and also keeps battery drain low. D1 keeps the input signal from driving the gate too high and D2, along with C2 and R3 form a peak rectifier. R1 is to minimize any distortion that might be added to the monitored line. I figured 9V batteries are everywhere guitar players and stomp boxes are, so chose that as power. Obviously, you can substitute or adapt design for other voltage but wouldn't recommend anything lower than about 5 V.

This might be a bit easier to read.....

CADENCE/OrCAD Schematic

KiCAD 7.0 Schematic


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[Voyager10]

Like THIS???.....
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Yes, that's got iit. If you were running off 9V probably the 470R resistor could be put up to 1K to keep the LED current down.