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Yes I have a bunch of inexpensive dc to dc switching boards, what we have to do is scope them and build in the protections we need, I have some older but good quality Tektronix scopes in my basement I need to bring up stairs, I get tired of running up and down as I prefer to work up stairs where I am close to my screens I love to watch, TV, laptops, security monitors are all up here, the problem is I have too much junk everywhere, I don't know where it all comes from, that and I can't understand how I fill up so many garbage bags every week, oh well I get lazy and just buy the ready made drivers, but now I need more amps so it's time to adapt, I have THIS for that 974nm that needs 12a @ around 4.8v so I will make it play nice as soon as I get off my lazy backside and scrape off enough space to bring up a scope. :)
 
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I bought some of those several years ago. They still don't work well in circuits that require very little current. Not too bad if you are pulling an ampere.
 
If it's within spec I don't see a problem although it does say ( Up to 12a ) but I was thinking 12vin to get my 4.6v out @ 12a, you will of course need to have a VIN greater than the voltage out by the minimum dropout margin as the unit I have is a step down only but you know that.

My issue with these has been startup spikes. As I want 12a @ 4.6v I can use a 0.4 ohm load that can take 60w to set it and test with, I could remove the pots and use resistors to make sure the reference is stable and maybe even set it up to use a start up load and switch in my device, I could also give it a shut down/restart timer and a shut down shunt/disconnect.

I will still need to make sure the power is clean, I was planning to drive it with 12v worth of lion cells, maybe 9 x 26650's in 3 strings of 3 cells series parallel, I was not going to use this driver for anything else so it only needs to handle this load well.

First I will scope it with a 0.4 ohm load and see what it's putting out, switch it on and off after setting it and see how it holds up as the cells discharge.

Thinking about it I may want to use diodes that add up to 0.4 ohms because diodes react differently to an overshoot than resistors and could reveal an otherwise unseen problem.
 
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how about a soft-start to help with startup overshoot?
the smps controller may have a pin for soft-start and just not being used due to cheap corner cutting of mfg.
maybe inductor current build-up issues?

soft-start-01.png
 
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the circuit i posted cold be its own board.

RedCowboy said:
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the smps controller should be the 5 pin TO-220 package on that heat-sink?
Judging by the photo. also looks like there using a mosfet or transistor to boost current ability.

the LM358 Op-amp could be important and a possible point for modification.
^^ Edit: main thing im trying to say is: possible point for modification.
 
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I have a bunch of LM358s in my stock. They come in handy if you need an OP amp or two. I've got a lot of these kinds of ICs as I am always trying some new way to try to make something that already exists in a different way. Every so often I have to go back and look at everything I've got as stuff slips my mind after awhile. Is this part of your attempt to make a driver for that 40 watt IR fiber optic coupled array you have?
 
I'm thinking about repurposing existing dc to dc boards and also how I can build my own, yes I am thinking to use the 12a dc to dc for a 30w 974nm that runs on 4.6v @ 12a however I may also build my own, I'm going to learn about these operational amps, they have been around since WWII, I saw where they were used in proximity devices to make shells more accurate back in the 40's, I am still learning.
 
Yeah, they have been around longer than the ICs they are now in. They are called operational amplifiers because they can be set up to effectively do integration, differentiation, summing, ect. I remember having to build them discretely in school.
 
I mixed that up, it was the early radar that used the a vacuum tube op amp, the proximity fuses used a simple RF oscillator that changed when it got close to ground, but that was enough to make shells a lot more effective.
 
Yes. I'm old enough to have worked with vacuum tubes too. Haven't seen any in a while, though. They are still used for certain high power applications. I have had my hands on some really old ones. From back in the early 40s. None of them were very small back then.
 
RedCowboy said:
Yes I have a bunch of inexpensive dc to dc switching boards, what we have to do is scope them and build in the protections we need, I have some older but good quality Tektronix scopes in my basement I need to bring up stairs, I get tired of running up and down as I prefer to work up stairs where I am close to my screens I love to watch, TV, laptops, security monitors are all up here, the problem is I have too much junk everywhere, I don't know where it all comes from, that and I can't understand how I fill up so many garbage bags every week, oh well I get lazy and just buy the ready made drivers, but now I need more amps so it's time to adapt, I have THIS for that 974nm that needs 12a @ around 4.8v so I will make it play nice as soon as I get off my lazy backside and scrape off enough space to bring up a scope. :)
Click to expand...

I got one of those recently, but haven't used it much. I shorted it on an ammeter, turned it up to 8A, the output voltage was practically nothing probably because of the short circuit (the load was I think 22AWG aluminum wire). It has a different chip on each heatsink, one gets way hotter than the other. For continuous use at 8-12A I'd the heatsinking on the front and back of the hot chip and put a strong computer fan on it. These chinese power supplies are usually overrated and need help.

I had a buck converter once that, with no load, I noticed would have a voltage spike above it's rated output when the power is connected. I connected power a few times in a row and blew the tantalum caps. I asked the mfg about it, and and we eventually concluded their analog volt meters couldn't show the spike like my digital meter could, so they claimed to have switched to digital. I haven't tested the upgrade circuit for spikes though.
 
Nutball said:
I got one of those recently, but haven't used it much. I shorted it on an ammeter, turned it up to 8A, the output voltage was practically nothing probably because of the short circuit (the load was I think 22AWG aluminum wire). It has a different chip on each heatsink, one gets way hotter than the other. For continuous use at 8-12A I'd the heatsinking on the front and back of the hot chip and put a strong computer fan on it. These chinese power supplies are usually overrated and need help.

I had a buck converter once that, with no load, I noticed would have a voltage spike above it's rated output when the power is connected. I connected power a few times in a row and blew the tantalum caps. I asked the mfg about it, and and we eventually concluded their analog volt meters couldn't show the spike like my digital meter could, so they claimed to have switched to digital. I haven't tested the upgrade circuit for spikes though.
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Yes if your output is shorted you wont be able to read any voltage, much like setting your table top power supply you won't see voltage when driving a short, that's why we need a load, also I was thinking about using some non light emitting diodes to add up to 0.4 ohms when testing as diodes may load differently than resistors from a cold start, I expect a ramp up circuit will be needed and I will also need to see what it does at shutdown on the output side, I am not looking to make it perfect for any load or idiotproof as it's for a specific laser module and it's on the back burner ATM until I clean up and bring up a scope from the basement, my house is packed with good junk and it's hard to throw any of it away, but I have been reasonable about what's likely to be useful lately, old working BW CRT sets are not going to get used so I have thrown some out....anyway when I engineer a workaround for it I will post about it, I would also like to try building some switching drivers, I have a retired electronics engineer in the family who would enjoy a project when we make time for it, so unless I find something for sale that fits the bill in the meanwhile or someone posts a workaround....heck I have not even tested this one yet, but I have tested/used others and you have to treat them like a table top PS to use them to avoid an overshoot, even the board with " memory " I read has issues.

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GSS said:
That's some nice Plumbing!:eek:
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Yea, they bring in a lot of cool builds at HOONIGAN, theres a sportsman series desert truck that rips the place up, those trucks are built to take one hell of a beating, and the boosted engines today are making 4 digit power regularly and sound great, I could listen to them scream all day.

I get caught up watching these rock bouncers hill climb too, many of these hills are so much steeper than the camera makes them look, but then you catch an angle that really shows how steep they are, they like the naturally aspirated LSX454 and 572 a lot sometimes with NOS, always injected, I doubt anyone runs a carb and some do use forced induction, but a lot of those NA engines are just old school built for a broad power band and sound good.

Listen to the green buggy at 10:45, sounds great huh ?

 
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