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LED strobe circuit needs more current

(*steve*)

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Steve said that, someone on the staff hooked me up with that avatar shortly after I joined...

There is, in general, only one person to blame for that sort of thing...
 

CDRIVE

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There is, in general, only one person to blame for that sort of thing...

I guess CC joined with that handle and you had an avatar that needed a home with a good fit.

Chris
 

trondyne

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I agree. But he seems to have a fixation on using these PCBs which are based on that design. I wasn't inclined to continue with that design, but I was able to make several improvements without hugely changing the circuit.

Hmmm canny... :confused: I had posted a whole list of reqs for it...

But unfortunately I am in the area hit by the storm in the NE USA...no power, heat nor hot water in the house--and cannot do much on this now..

I was keen on the PCB in question because I can get those without going through a production cycle..but I am having second thoughts now..after wasting so much time on this.. So I guess I will have go though an entire production cycle $$$, something I don't have any experience doing and I am hoping I can get some help with...

Nevertheless, I am getting tired of playing with this design, one not really suited to what I need..which mainly is to simulate a single strobe effect with variable timing via a pot at about 1 watt per channel max (2 channels) (revised spec) current limiting for the LEDs to be handled post outputs.. Power source for final models will either be a 4.8v pack or regulated 5v. PCBs should be small about 3cm x 2.5cm max, components should be large enough to assemble and solder by hand..

So, when I finally get power back in the house I will work on doing a new design for this primary circuit.

I will try to post additional and perhaps slightly more ambitious specs for the new design when I get back into the 21st century.. It's quite maddening living without power in the NE US for extended periods..

I do thank everyone for the ideas so far I continue to learn more and hopefully I will make it though to getting some kind of prototype going..

Cheers,

Jim
 
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CDRIVE

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You began this thread wanting to strobe a single high current LED with a simple circuit. I took the time to give you this a few posts back but you didn't acknowledge it. Perhaps Sandy caused you to miss it.

Chris

5998d1351528067-led-strobe-circuit-needs-more-current-555-tlc-astable.jpg
 

KrisBlueNZ

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Hmmm canny... :confused: I had posted a whole list of reqs for it...
Yes, canny. It took me a special request just to get the power supply information out of you.

Everyone on electronics forums likes to help, but you really can save us a lot of time and effort by giving us a thorough description of what you want to do, and all the factors that have been decided. There is so much information you could have provided that you still haven't. The message I'm replying to has some of the kind of information that you should have provided up-front.

But unfortunately I am in the area hit by the storm in the NE USA...no power, heat nor hot water in the house--and cannot do much on this now..
I'm really sorry to hear that. Sandy has been big news here and everyone is upset about it.

I was keen on the PCB in question because I can get those without going through a production cycle..but I am having second thoughts now..after wasting so much time on this.. So I guess I will have go though an entire production cycle $$$, something I don't have any experience doing and I am hoping I can get some help with...
Have you tried the suggestions I gave for modifying the original design?
 

trondyne

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Yes, canny. It took me a special request just to get the power supply information out of you.

Everyone on electronics forums likes to help, but you really can save us a lot of time and effort by giving us a thorough description of what you want to do, and all the factors that have been decided. There is so much information you could have provided that you still haven't. The message I'm replying to has some of the kind of information that you should have provided up-front.


I'm really sorry to hear that. Sandy has been big news here and everyone is upset about it.


Have you tried the suggestions I gave for modifying the original design?

Please forgive me.. I originally posted 5v as the input power and was not aware that was insufficient..I am a noob..

I have not had much of a chance to try anything since the storm hit.. As it is I have only limited access to the NET when I am at work and while at work my online activities are limited.

I had tried adding the additional output amp suggested by Harald. It seemed to help a bit but still did not seem to get the amps needed for some reason be it the brief time of illumination or some other feedback problem... As I said I am new to this stuff at this level and while I am having fun learning I am hitting a lot of stumbling blocks.. Hopefully I will have power back soon, and when I do i can continue working on this.. Thanks for everyone's help!

Jim
 

trondyne

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You began this thread wanting to strobe a single high current LED with a simple circuit. I took the time to give you this a few posts back but you didn't acknowledge it. Perhaps Sandy caused you to miss it.

Chris

5998d1351528067-led-strobe-circuit-needs-more-current-555-tlc-astable.jpg

Sorry I got busy trying this and then that... As I mentioned the storm has curtailed my work on this but all suggestions help.. I have to decide if i can work with the original circuit or change to this.. This is actually what I was looking at last just before the storm hit...yes Sandy. Con Edison has not even started fixing anything in my area...jeeez.

Again I do appreciate the help very much!

Thanks, I will keep reporting back if you guys can put up with me!! ;)

Jim
 

trondyne

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You began this thread wanting to strobe a single high current LED with a simple circuit. I took the time to give you this a few posts back but you didn't acknowledge it. Perhaps Sandy caused you to miss it.

Chris

5998d1351528067-led-strobe-circuit-needs-more-current-555-tlc-astable.jpg

Does this circuit create only and on/off signal or can it also create a strobe wave effect?
 

CocaCola

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Does this circuit create only and on/off signal or can it also create a strobe wave effect?

What is a strobe wave effect? Strobes in general just flash on and off rapidly...

CDRIVE's picture shows you the waveform output of the circuit, it's an on/off square wave...
 

CDRIVE

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Sorry to hear you're without power. Modern man is no longer equipped to live without it. Which is why I've always had a deep respect for country folk.

Chris

Edit: As CC said, my circuit produces a square wave. Actually, and to be more precise, it produces a repetitive brief pulse to mimic a strobe.
 
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KrisBlueNZ

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Please forgive me.. I originally posted 5v as the input power and was not aware that was insufficient..I am a noob..
I understand. It's just that when we ask questions, we ask them for a reason, even if the reason may not be obvious to you. It's frustrating when these questions don't get answered, especially if we ask them several times in a row.
I have not had much of a chance to try anything since the storm hit.
Yes, and I must apologise back to you Jim. You had said that before, and it was rude of me to hurry you along.
Kris
 

trondyne

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I understand. It's just that when we ask questions, we ask them for a reason, even if the reason may not be obvious to you. It's frustrating when these questions don't get answered, especially if we ask them several times in a row.

Yes, and I must apologise back to you Jim. You had said that before, and it was rude of me to hurry you along.
Kris

Well power is back! Many still without.

I worked for a while on your revision to the circuit Kris.. Hard to tell if the output was much higher.. In virtually all the configurations I have ran a standard 5mm red LED rated at 20ma will run which I assume means not much current is flowing.. The best result I have had so far I think was using Harald's add on final stage amp with a Darlington. This as I recall seemed to make for the brightest flash..

Ideally I would like to overdrive the LED or simply have no current limiting, since it will only be on for a short burst and test for reliability...and I need two channels so perhaps two added on transistor stages would be best IF I go with this circuit.. Eventually I need to go with a new design..

Jim
 
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trondyne

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What is a strobe wave effect? Strobes in general just flash on and off rapidly...

CDRIVE's picture shows you the waveform output of the circuit, it's an on/off square wave...

Well the effect is very important here.. I don't know if perhaps older strobes worked slightly differently than simply on/off.. This effect has a very short but perceptible ramp up to full power and off with perhaps a slight ramp down.. The effect is similar to a flash bulb--kind of a light explosion--and when a couple of folks saw the light when I was working with it they commented that it looked interesting, they said wow cool.. This is not the reaction when dealing with a simple on/off and the effect looks and feels different.. It is key to the effect I need here.

Jim
 
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trondyne

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You began this thread wanting to strobe a single high current LED with a simple circuit. I took the time to give you this a few posts back but you didn't acknowledge it. Perhaps Sandy caused you to miss it.

Chris

5998d1351528067-led-strobe-circuit-needs-more-current-555-tlc-astable.jpg

For the final design I would like to go with the 555 I think.. The key there would be to maintain the same flash bulb like strobe effect..

Jim
 

CocaCola

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The effect is similar to a flash bulb--kind of a light explosion--and when a couple of folks saw the light when I was working with it they commented that it looked interesting, they said wow cool.. This is not the reaction when dealing with a simple on/off and the effect looks and feels different.. It is key to the effect I need here.

Film it if you can... Flash bulbs are simply on/off nothing fancy or special about them ramping up, the circuit charges up and *POOF* an instantaneous on followed by a quick off... Same with old practical (powder or filament) or new xenon tubes...
 

trondyne

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Film it if you can... Flash bulbs are simply on/off nothing fancy or special about them ramping up, the circuit charges up and *POOF* an instantaneous on followed by a quick off... Same with old practical (powder or filament) or new xenon tubes...

I tried but the entire time it takes to ramp up and ramp down is too short to be captured accurately...

Didn't older strobes or some kinds of strobes light up slightly before they peak and likewise didn't they remain glowing slightly after peak? This is about milliseconds. I have seen some others talking about a non square wave when either talking about strobes or trying to simulate one.. A very fast ramp up and an even faster ramp down.. It does add to the effect. There must be something else that does this..lightning? Or perhaps some older strobe circuitry? I thought I remembered reading about older strobes perhaps with energy being stored in coils perhaps they would ramp up or leak, just a bit, a design limitation or perhaps time to full illumination of the bulb again talking milliseconds.

Jim
 
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CDRIVE

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That's why I set up the 555 for a brief pulse. That's what strobe effect is. R4 controls the pulse width. You can easily make it shorter or longer.

Chris
 

trondyne

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That's why I set up the 555 for a brief pulse. That's what strobe effect is. R4 controls the pulse width. You can easily make it shorter or longer.

Chris

Sure but there is no quick ramp up and down.. It should be possible to add that I would think.

One of the other circuits I need also needs a ramp up and down but much much longer and symmetrical--long ramp up to full on then equally long ramp down to full off then repeat.
 
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CocaCola

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There is no ramp up in a strobe, there is a charge up of a capacitor behind the scenes but until it's discharged there is no light to be seen, the light on discharge is instantaneous with no ramp up as it only last a few milliseconds... Same with flash powder and old filament flashes, no glow before hand just an instantaneous flash...

The ramp up you think you might be seeing is likely the human eyes inability to adjust fast enough and take it all in...

If you want a ramp up the circuit will get more involved... IMO digital is better as the ramp can be more tightly controlled, analog ramp ups of short duration are hard to control and adjust (at least no where near as easy as a digital circuit)... But, this is not the way a strobe works...
 
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trondyne

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There is no ramp up in a strobe, there is a charge up of a capacitor behind the scenes but until it's discharged there is no light to be seen, the light on discharge is instantaneous with no ramp up as it only last a few milliseconds... Same with flash powder and old filament flashes, no glow before hand just an instantaneous flash...

The ramp up you think you might be seeing is likely the human eyes inability to adjust fast enough and take it all in...

If you want a ramp up the circuit will get more involved... IMO digital is better as the ramp can be more tightly controlled, analog ramp ups of short duration are hard to control and adjust (at least no where near as easy as a digital circuit)... But, this is not the way a strobe works...

Well the first circuit does a nice effect regardless.. If I could get two output channels to replicate the wave and put out good power I could get past this first problem.. As it is it just doesn't seem to peak at full power even with no current limiting resistor. As I said I can even run a cheapo red 20ma LED in these different configs without it blowing so I assume the light is not getting much power...

Maybe I'll just move on to the next controller and try to incorporate this function into that..
 
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