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Boost converters?


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#1 Phil

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Posted 16 January 2021 - 05:54 PM

I built a 1 cue remote firing circuit a while back with one of those generic 12v RF relays you find all over ebay and while it worked wonderfully with the 12v wall adapter I was using to power it, switching it over to battery power doesn't seem to be going so smooth. I had my homemade wirewound igniters dialed in for that power supply, they would glow almost white hot after a half second or so of holding the button. I had 4 rechargable NIMH AA batteries laying around and decided to utilize those. Measuring from the holder I get 5.1V which is within input range for the converter I have. I have the output adjusted to 12V and it seems to power everything fine up until the moment I go to power an igniter. I feel like it's shorting. The relay opens and closes very rapidly, it sounds like buzzing (like if I was to bridge the output speaker terminal with a paperclip). Before switching over to batteries I measured the current pull with my igniters at 1.5AMPS. Where am I going wrong?

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#2 Carbon796

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Posted 16 January 2021 - 10:18 PM

Sounds like the boost converters output probably needs to be rectified and or filtered. Your probably energizing the DC relays coil, at the converters operating frequency.

#3 Phil

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Posted 16 January 2021 - 10:32 PM

How would I go about that? I have some caps and diodes. I assume cleaning up the output would involve those.

I tried placing a cap (I have 330uf, 470uf and 1000uf) after the converter's output and it slowed the frequency of the relay module opening and closing enough to where it no longer sounds like buzzing however it's not staying closed even remotely long enough to heat up the igniter. The linked video demonstrates the result as I hold the button down.https://streamable.com/739h2f


Edited by Phil, 17 January 2021 - 12:08 AM.


#4 Arthur

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Posted 17 January 2021 - 02:58 AM

The change that you made that stopped it working was to change the power supply, look again at that. what do you have? Could you use a 12v sealed lead acid battery from an alarm or from a lawn tractor(etc). could you use 12v in the form of a tool battery (drill etc) could you use 12v from a series pack of AA batteries, or a 12v lantern battery. 



#5 Phil

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Posted 17 January 2021 - 08:13 AM

I wasn't using the converter before either. I suppose I COULD change the source, however the idea was that whatever I ended up using was compact enough to fit in this box. If I absolutely can't get what I need with what I have from 4 AAs I could order some other type of pack or construct my own, the question is what do I use? You mentioned tool batteries, is it possible to use 18650 batteries or something of the like to get 12v and what would I need? Would something like this work as a cheaper option? https://www.ebay.com...ip/363075958099


Edited by Phil, 17 January 2021 - 09:25 AM.


#6 Richtee

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Posted 17 January 2021 - 10:25 AM

Just get a 12V 7-8 AH gel cell. An alarm battery. Plenty of balls for what you need. And a 12V trickle charger. Prolly all together $40.


Edited by Richtee, 17 January 2021 - 10:25 AM.

I like smoke! On food or in the air equally well.

#7 SeaMonkey

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Posted 18 January 2021 - 06:19 PM

Four AA size NiMH cells series connected to provide a nominal 5.2 Volts to the

Boost Converter for a 12 Volt Output will not be effective.

 

The AA size NiMH cells cannot provide sufficient current to sustain a hefty 12 Volt

output for more than a few seconds.  NiMH cells aren't designed for heavy current

output as the NiCd cells of earlier times were.

 

A 12 Volt Sealed Lead-Acid battery would do the trick as Richtee suggested.

 

Or, four Lithium Cells series connected to provide about 14 Volts would also do

well and would fit within your plastic box.

 

Boost Converters need a battery source that is capable of supplying heavy

current in an application such as you have.  5 to 6 Volts at the Input to the

Converter with the capability to supply about 10 Amperes for several minutes

would be enough reserve energy to provide the Amperage at 12 Volts in order

to ignite your electrical ignitors quickly.



#8 Arthur

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Posted 19 January 2021 - 12:37 PM

The trouble with boost converters is that they get the volts from the supply at the cost of increased current draw. Likely a really big 6v supply would work through the converter as would a 12v 0.8Ah SLA or bigger.



#9 Richtee

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Posted 19 January 2021 - 04:31 PM

I still think he’s trying to computerize a toilet :D

 

Get a damn gel cell and be done with it.

 

https://www.homedepo...ds&locale=en-US

 

https://www.homedepo...ds&locale=en-US

 

There’s an engineering principle I learned early on... called the “KISS” principle. I bet some of ya heard of it :D


Edited by Richtee, 19 January 2021 - 04:33 PM.

I like smoke! On food or in the air equally well.

#10 Phil

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Posted 20 January 2021 - 04:41 PM

I think I'll try richtee's suggestion and grab one of those 12v lead acid batteries. Wouldn't be in the box like I wanted but it's progress and better than running an extension cord. I'll figure out the downsizing part later when I get everything together with something a bit more permanent than a breadboard. Hasn't totally been time wasted because now I got a few extra gadgets sitting around that I now know aren't exactly as straightforward as I expected. Guess I know one more way not to do it.Thanks guys.



#11 Richtee

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Posted 20 January 2021 - 09:22 PM

 Guess I know one more way not to do it.Thanks guys.

Thomas Edison..I think it was said “I have not failed. I have found 10,000 ways that do not work"

 

Carry on soldier.


I like smoke! On food or in the air equally well.

#12 Arthur

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Posted 21 January 2021 - 01:56 AM

A quick search on Mouser's www shows SLA batteries from 200mAH, I'm sure you could find something to fit your box and fit the function. The Chinese, Kingdom 20 chan remote controller works fine and contains a 800mAH 12v sealed lead battery.



#13 Richtee

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Posted 21 January 2021 - 06:01 AM

Yeah, you probably don’t need 7 or 8 AMP-hours. That’s just an easy to find bat. But they weigh like 5 pounds. 800mAH is sufficient? I’d think that on the low end... but I dunno... never fired electrically.


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#14 Arthur

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Posted 21 January 2021 - 12:12 PM

An important point to remember is that a professional firework igniter fires at about 500mA for 20 milli seconds BUT a DIY igniter may take 2 - 5 amps for a second or two. The psu and the wiring must be up to the firing current required.



#15 Richtee

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Posted 21 January 2021 - 01:28 PM

An important point to remember is that a professional firework igniter fires at about 500mA for 20 milli seconds BUT a DIY igniter may take 2 - 5 amps for a second or two. The psu and the wiring must be up to the firing current required.

Fer sher. Were I designing a system the “snake” would prolly be 18 ga. Actually what I might do is use 24VDC as well. That would about halve the current required, therefore the wire size to maybe 20 ga. 20 ga multi-conductor cables ain’t too hard to come by. Might even get away with Cat 6 if yer not running 100 foot of it.


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#16 SeaMonkey

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Posted 21 January 2021 - 04:27 PM

Don't  forget the Li-Ion cells or batteries.

They're a bit more expensive but can deliver a LOT of current.

 

They're also small, lightweight and have remarkable Ampere Hour capacity for their size and weight.

 

The SLA is, however, the best economical choice.



#17 Phil

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Posted 21 January 2021 - 07:26 PM

An important point to remember is that a professional firework igniter fires at about 500mA for 20 milli seconds BUT a DIY igniter may take 2 - 5 amps for a second or two. The psu and the wiring must be up to the firing current required.


This is precisely the lesson I'm learning now. I think my igniters are pretty crude(I haven't figured out the pyrogen part yet) and when measured with a multimeter they pulled 1.5 amps with the wall adapter. I could hold the one in the picture for 30 seconds at a time and it wouldn't burn out. I'm guessing this will light anything short of a wet shoestring. (fuses, BP, carpets...) https://imgur.com/lIBSeyF


Edited by Phil, 21 January 2021 - 07:29 PM.


#18 Phil

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Posted 21 January 2021 - 07:37 PM

Don't  forget the Li-Ion cells or batteries.

They're a bit more expensive but can deliver a LOT of current.

 

They're also small, lightweight and have remarkable Ampere Hour capacity for their size and weight.

 

The SLA is, however, the best economical choice.

Lion batteries like this? https://www.ebay.com...hc7dR1&LH_BIN=1

Duly noted.


Edited by Phil, 21 January 2021 - 07:37 PM.


#19 SeaMonkey

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Posted 22 January 2021 - 07:40 PM

Question from Phil:

 

Lion batteries like this?

 

 

That Battery Pack would surely do the job.

 

Its price is surprising.  The Lithium Batteries are becoming quite affordable.



#20 WRAITH

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Posted 12 February 2021 - 07:30 PM

For boosting power, try using a voltage amplifier circuit or a plasma lighter circuit as they use only 3.7v, but give a high voltage output (electric arc that burns) or if you are using cheap throw away batteries, i suggest building a small joul thief circuit. You may want to add a capacitor to store more energy & smooth out voltage.




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