Buck or boost converter that ramps up and down

Starlight

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I need a DC-DC converter (buck or boost) that will ramp up and down with the power switch. Continuously or step variable. Output power up to about 10A. If you can give me a recommendation, please help.
 

Macgravy

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I, for one, need some additional information. You stated "Output power up to about 10A". Output power is measured in Watts. This is Output Current. So you need a converter that has a capibility of providing 10 Amps of current. Now we need the voltage input & output range? Thanks.
 

Starlight

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Sorry for the confusion. I'm not real limited on range, depends whether it is buck or boost. Say 6v to 30v input and 6v to 30v on output. Any variation outside that range would be better. I'm thinking about 300W capability. I don't have a specific project in mind, I will base it on what is available in converters.
 

sbj

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Not just a converter, but an extremely universally applicable charger: Junsi iCharger X6:


But can at the input from 7 to 32V up to 35A; at the output 2 to 26.5V up to 30A (max. 800W).


Can also charge, discharge and store all common battery chemistries. And has a display that shows all important data on one screen.
 

alpg88

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what is it for? do you need a portable board to use inside a device, or you need it to use as desktop power supply?
 

sbj

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If your question was directed at me?
The charger has a mode where you can simulate a laboratory power supply.

You can therefore set the output voltage and the maximum output current.

Described in the operating instructions on page 22.
 

Starlight

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Let's approach this slightly differently. I am trying to power a portable light. I have found the following converters on ebay. All of them would work for what I am planning, but none of them have the ramp up and down feature. I need someone to tell me how to add the ramping feature to one of these, or recommend a similar converter that already has the ramping feature.

https://www.ebay.com/itm/275369682429

https://www.ebay.com/itm/2854592413...oEer27+iMrPAZ01UP1kHNOmw==|tkp:Bk9SR4ys2MTfYg


https://www.ebay.com/itm/3746782613...JYXjuu3qNk5P4EnmxYN14XK8w=|tkp:Bk9SR4isvsXfYg
 

Dave_H

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I need a DC-DC converter (buck or boost) that will ramp up and down with the power switch. Continuously or step variable. Output power up to about 10A. If you can give me a recommendation, please help.
A lot of questions:

Specifically what type of lighting are you driving, incandescent, LED, and if latter does it use a driver? What kind of load current?

What ramp up/down times are you looking for, i.e. 1 second, or 5-10 seconds etc. I take it this is for aesthetic purposes?

Depending on the light, ramping its voltage up and down linearly may not produce the result you want.

Are you able to narrow down the input and output voltage ranges? Does it actually need to buck and boost? Those types are typically more complex and expensive than a pure buck or boost converter.

Rather than a special power supply which might require ramping for lab or testing use, it may be easier/cheaper to add a circuit/module between supply and lighting. I don't have specific suggestion at this point.

Looking at the eBay items, I'd be a bit skeptical of some of their specs, at those prices.

What's your budget for all of this?


Dave
 

Starlight

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A lot of answers.

Incandescent.

Ramp time--don't care

Buck, boost, or buck/boost--don't care

Adding a module would be fine, but I don't know what I need.

Budget--cheap

Just show me some options, then I can decide what I want.
 

Dave_H

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A lot of answers.

Incandescent.

Ramp time--don't care

Buck, boost, or buck/boost--don't care

Adding a module would be fine, but I don't know what I need.

Budget--cheap

Just show me some options, then I can decide what I want.
What voltage are the lamps designed to run on?

I am thinking a 12v/24v dc lamp dimmer may have this feature, without manually have to dim up and down; but no specific advice.

Dave
 

Dave_H

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Incandescents would require a fixed voltage output supply. A constant-current supply would only work if you can set it to the current corresponding the the lamp wattage e.g. a 24W lamp at 12v is 2A. If you change to different lamp (voltage and/or wattage), current setting would have to be changed. It's not usually done this way. CC is mainly used for LEDs.

Using voltage-output buck converter, its input voltage needs to be higher than the highest voltage of bulb being used.

Unless you can narrow down your input and output requirements, getting a "one-size-fits-all" solution which works correctly for all cases is going to be difficult.

Dave
 

Starlight

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Lamps I am considering are 12v 100W, 24v 250W, 28v 600W and 36v 400W. Say a buck for 12v and 24v, and a boost for 28v and 36v. I will not be changing lamps. I will have one converter/system and lamp for one light. If I want to use a different lamp, it would be in a different light and another converter.

I'm not asking for a one size fits all, just something that will work for one setup.
 

Macgravy

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Running Incandescents on DC will cut their life by more than 50% if ran at rated voltage....Incandescents rated life is on AC only at rated voltage. Now with that said, you can greatly increase their life by decreasing the voltage source. I use to have those equations handy, but I'm guessing they are on the web somewhere. I think I would just try to find some big transformers and use them. Just 1 more choice to consider.
 

sbj

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Low-voltage halogen lamps are already designed to operate with direct current.
But there are types from the same manufacturer with different lifespans.

For example Osram 24V150W:
64640: 50 hours;
64641: 200 hours;
64642: 300 hours;

However, it is still true that the lifespan decreases if the lamps are operated with a little more than the nominal voltage, or increases if the voltage is lower.
 

Starlight

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I'm not worried about lamp lifespan, I know how to use buck and boost converters. What I want to know, is there a converter with a dimming feature on the converter, or how do I add dimming to a circuit.
 
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Dave_H

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Lamps I am considering are 12v 100W, 24v 250W, 28v 600W and 36v 400W. Say a buck for 12v and 24v, and a boost for 28v and 36v. I will not be changing lamps. I will have one converter/system and lamp for one light. If I want to use a different lamp, it would be in a different light and another converter.

I'm not asking for a one size fits all, just something that will work for one setup.
OK, understanding better what you are trying to do. What voltage(s) are feeding your convertors, or is that decided?

Running buck for 12v or 24v means input above 24v; and boost for 28v and 36v implies something below 28v, so I'm thinking 26v would work for either case?

Dave
 

Macgravy

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Are you really using Low-voltage halogen lamps?

Also, are you planning to use a power supply to drop the mains voltage to some voltage the converters can use, which brings up the question, Why?

Or are you using something like an couple of automobile batteries wired in series to come up with ~24VDC, thereby you stating the use of buck converter for the 12v and 24v lamps and boost converter for the 28v and 36v lamps. Running a buck converter and trying to maintain 24 volts to the lamp(s) will be difficult on 2 series auto batteries.
 

Dave_H

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Are you really using Low-voltage halogen lamps?

Also, are you planning to use a power supply to drop the mains voltage to some voltage the converters can use, which brings up the question, Why?

Or are you using something like an couple of automobile batteries wired in series to come up with ~24VDC, thereby you stating the use of buck converter for the 12v and 24v lamps and boost converter for the 28v and 36v lamps. Running a buck converter and trying to maintain 24 volts to the lamp(s) will be difficult on 2 series auto batteries.
My thought also, two convertors in series, "compound" inefficiency.

I'd also be careful with the specs of some of those cheap er low-cost dc-dc convertor modules from you-know-where, they seem optimistic. 300W at 96% efficiency in a module that size costing less than US$10? Caveat emptor.

Dave
 
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