12V to 5V conversion

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My nephew is mucking about with home automation stuff and has wiring in his
 place for an alarm system.  The original panel is still there with 12 volt
 power.  He is asking me about using that to mount an iPad with 5 volt powe
r.  We found various adapters to go from the wiring to the connector needed
 (wire to USB A and USB to Lightning) for charging.  Now I'm looking at 12  
to 5 volt power converters.  This one looks good, but there's no info on wh
ether it is switching or linear.  

https://www.superbrightleds.com/moreinfo/installation-power/12-vdc-to-5-vdc
-step-down-convertervoltage-reducer/1549/3652/

I'm thinking in such a small module it would have to be a switcher since it
 handles 3 amps.  But then I'm also concerned about noise, so I'm going to  
recommend he add a couple of caps to the input and output.  Anyone familiar
 with this product?  Know of better ones?  

The tablet will charge at 1 Amp, but operation often is significantly less.
  I'll remind him to find some software that will keep the charge level bel
ow 75% to make the battery last.  

--  

  Rick C.

  - Get 1,000 miles of free Supercharging
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Re: 12V to 5V conversion

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is place for an alarm system.  The original panel is still there with 12 vo
lt power.  He is asking me about using that to mount an iPad with 5 volt po
wer.  We found various adapters to go from the wiring to the connector need
ed (wire to USB A and USB to Lightning) for charging.  Now I'm looking at 1
2 to 5 volt power converters.  This one looks good, but there's no info on  
whether it is switching or linear.  
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dc-step-down-convertervoltage-reducer/1549/3652/
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it handles 3 amps.  But then I'm also concerned about noise, so I'm going t
o recommend he add a couple of caps to the input and output.  Anyone famili
ar with this product?  Know of better ones?  
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s.  I'll remind him to find some software that will keep the charge level b
elow 75% to make the battery last.  
Quoted text here. Click to load it

there is tons of modules like these on Ebay etc.
https://www.ebay.co.uk/itm/392803873279

or just go to a random electronics store and buy a USB car charger






Re: 12V to 5V conversion
On Friday, July 10, 2020 at 6:30:12 PM UTC-4, Lasse Langwadt Christensen wr
ote:

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 his place for an alarm system.  The original panel is still there with 12  
volt power.  He is asking me about using that to mount an iPad with 5 volt  
power.  We found various adapters to go from the wiring to the connector ne
eded (wire to USB A and USB to Lightning) for charging.  Now I'm looking at
 12 to 5 volt power converters.  This one looks good, but there's no info o
n whether it is switching or linear.  
Quoted text here. Click to load it
-vdc-step-down-convertervoltage-reducer/1549/3652/
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e it handles 3 amps.  But then I'm also concerned about noise, so I'm going
 to recommend he add a couple of caps to the input and output.  Anyone fami
liar with this product?  Know of better ones?  
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ess.  I'll remind him to find some software that will keep the charge level
 below 75% to make the battery last.  
Quoted text here. Click to load it

And plug it into what???  "Random" is not a selection criteria.  I'm lookin
g for something that will work well, not the usual crap sold on ebay or ali
express.  I bought a cheap USB wall charger once and when it would no longe
r charge my flip phone (in spite of putting out 3.3 volts) it didn't even h
ave a chip, just a single transistor.  Looking for something of better qual
ity and in a decent package which is what this unit clearly does, just not  
sure of the guts.  

Looking for 12 volts wired to 5 volts either wired or USB A female.  I supp
ose even a microUSB output would do the job.  I would like for it to be a s
witcher and rated for at least 1.5 amps.  

--  

  Rick C.

  + Get 1,000 miles of free Supercharging
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Re: 12V to 5V conversion

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wrote:

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in his place for an alarm system.  The original panel is still there with 1
2 volt power.  He is asking me about using that to mount an iPad with 5 vol
t power.  We found various adapters to go from the wiring to the connector  
needed (wire to USB A and USB to Lightning) for charging.  Now I'm looking  
at 12 to 5 volt power converters.  This one looks good, but there's no info
 on whether it is switching or linear.  
Quoted text here. Click to load it
-5-vdc-step-down-convertervoltage-reducer/1549/3652/
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nce it handles 3 amps.  But then I'm also concerned about noise, so I'm goi
ng to recommend he add a couple of caps to the input and output.  Anyone fa
miliar with this product?  Know of better ones?  
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 less.  I'll remind him to find some software that will keep the charge lev
el below 75% to make the battery last.  
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ing for something that will work well, not the usual crap sold on ebay or a
liexpress.  I bought a cheap USB wall charger once and when it would no lon
ger charge my flip phone (in spite of putting out 3.3 volts) it didn't even
 have a chip, just a single transistor.  Looking for something of better qu
ality and in a decent package which is what this unit clearly does, just no
t sure of the guts.  
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ppose even a microUSB output would do the job.  I would like for it to be a
 switcher and rated for at least 1.5 amps.  
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and that is what you from a USB charger meant to plug into a cars cigarette
 lighter, it'll even have the pins in the required state to make a phone/ta
blet recognise it as a charger  




Re: 12V to 5V conversion
On Friday, July 10, 2020 at 7:04:18 PM UTC-4, Lasse Langwadt Christensen wr
ote:

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n wrote:

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g in his place for an alarm system.  The original panel is still there with
 12 volt power.  He is asking me about using that to mount an iPad with 5 v
olt power.  We found various adapters to go from the wiring to the connecto
r needed (wire to USB A and USB to Lightning) for charging.  Now I'm lookin
g at 12 to 5 volt power converters.  This one looks good, but there's no in
fo on whether it is switching or linear.  
Quoted text here. Click to load it
to-5-vdc-step-down-convertervoltage-reducer/1549/3652/
Quoted text here. Click to load it
since it handles 3 amps.  But then I'm also concerned about noise, so I'm g
oing to recommend he add a couple of caps to the input and output.  Anyone  
familiar with this product?  Know of better ones?  
Quoted text here. Click to load it
ly less.  I'll remind him to find some software that will keep the charge l
evel below 75% to make the battery last.  
Quoted text here. Click to load it
oking for something that will work well, not the usual crap sold on ebay or
 aliexpress.  I bought a cheap USB wall charger once and when it would no l
onger charge my flip phone (in spite of putting out 3.3 volts) it didn't ev
en have a chip, just a single transistor.  Looking for something of better  
quality and in a decent package which is what this unit clearly does, just  
not sure of the guts.  
Quoted text here. Click to load it
suppose even a microUSB output would do the job.  I would like for it to be
 a switcher and rated for at least 1.5 amps.  
Quoted text here. Click to load it
te lighter, it'll even have the pins in the required state to make a phone/
tablet recognise it as a charger

It is a completely wrong form factor.  It would need to be torn apart and r
ebuilt.  Neither the person using this nor myself want to bother with that  
when the perfect form factor is available.  

Then there is the tiny issue that 95% of the stuff for phone charging is co
mplete crap.  I'm always scared to use much of it until it has been thoroug
hly tested.  Not worth the bother for this.  That's why I am asking for rec
ommendations.  To avoid the crap products.  

Thanks for the idea anyway.  

--  

  Rick C.

  -- Get 1,000 miles of free Supercharging
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Re: 12V to 5V conversion
On Friday, July 10, 2020 at 6:30:12 PM UTC-4, Lasse Langwadt Christensen wr
ote:

Quoted text here. Click to load it
 his place for an alarm system.  The original panel is still there with 12  
volt power.  He is asking me about using that to mount an iPad with 5 volt  
power.  We found various adapters to go from the wiring to the connector ne
eded (wire to USB A and USB to Lightning) for charging.  Now I'm looking at
 12 to 5 volt power converters.  This one looks good, but there's no info o
n whether it is switching or linear.  
Quoted text here. Click to load it
-vdc-step-down-convertervoltage-reducer/1549/3652/
Quoted text here. Click to load it
e it handles 3 amps.  But then I'm also concerned about noise, so I'm going
 to recommend he add a couple of caps to the input and output.  Anyone fami
liar with this product?  Know of better ones?  
Quoted text here. Click to load it
ess.  I'll remind him to find some software that will keep the charge level
 below 75% to make the battery last.  
Quoted text here. Click to load it

Grin.  There's also these three terminal (switching)
 voltage regulators... Not 3 amps though.  

George H.  

Re: 12V to 5V conversion
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In that size it's switching.  ther's no way that plastic pack could
dissipate 21W

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I'm a fan of the "MH" branded open XL4015 modules.

They cost under two bucks and at 2A load they run just barely warm.

https://www.aliexpress.com/item/32828503015.html

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seeing as the supply is 12V something like Mini 360 (max input voltage
17V) would be an option too.

under a buck,

https://www.aliexpress.com/item/32705615262.html

under half a buck at qty 10.

https://www.aliexpress.com/item/32710902622.html


But with Aliexpress, Ebay, Banggood, Amazon, etc you're buying from a reseller
who may not understand their wares.

These guys are good and price their stuff in the same ballpark:

https://www.qskj.cc/

This module has solder jumpers for several convenient preset voltages after you cut the track to the potentometer  
https://www.qskj.cc/shop/product/1941621-mini-dc-dc-buck-step-down-module-4-24v-12v-24v-to-5v-3a-power-module-qs-1205cme-3a-79148

I'd de-rate it to 1.5A continuous, 3A surge.  

--  
  Jasen.

Re: 12V to 5V conversion

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 his place for an alarm system.  The original panel is still there with 12  
volt power.  He is asking me about using that to mount an iPad with 5 volt  
power.  We found various adapters to go from the wiring to the connector ne
eded (wire to USB A and USB to Lightning) for charging.  Now I'm looking at
 12 to 5 volt power converters.  This one looks good, but there's no info o
n whether it is switching or linear.  
Quoted text here. Click to load it
-vdc-step-down-convertervoltage-reducer/1549/3652/
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ess.  
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elow 75% to make the battery last.  
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eller
er you cut the track to the potentometer  
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-4-24v-12v-24v-to-5v-3a-power-module-qs-1205cme-3a-79148
Quoted text here. Click to load it

the boards are fine, but be sure to check the output voltage, the presents  
never match

Re: 12V to 5V conversion
On Friday, July 10, 2020 at 8:32:47 PM UTC-4, Jasen Betts wrote:
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 his place for an alarm system.  The original panel is still there with 12  
volt power.  He is asking me about using that to mount an iPad with 5 volt  
power.  We found various adapters to go from the wiring to the connector ne
eded (wire to USB A and USB to Lightning) for charging.  Now I'm looking at
 12 to 5 volt power converters.  This one looks good, but there's no info o
n whether it is switching or linear.  
Quoted text here. Click to load it
-vdc-step-down-convertervoltage-reducer/1549/3652/
Quoted text here. Click to load it

What about EMI?  My nephew would need to package this since it is going ins
ide a wall box.  I guess the better place for this is not the end outlet bo
x, but the main box which is probably over a foot square and can probably d
issipate some heat.  The odd thing is the transformer that powers this is i
n the attic while the panel is somewhere else.  Why would they put the powe
r source in the attic???  


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ess.  
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elow 75% to make the battery last.  
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eller
er you cut the track to the potentometer  
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-4-24v-12v-24v-to-5v-3a-power-module-qs-1205cme-3a-79148
Quoted text here. Click to load it

If you recommend these guys...  but do they make any of this stuff or just  
resell it?  This one is interesting as it has the USB connector built in.
  

https://www.qskj.cc/shop/product/1941681-dc-dc-step-down-module-6-24v-12v-2
4v-to-5v-3a-power-supply-charger-qs-1205cbul-3a-79151?category26%73

They talk about a 1.5 amp input fuse, I see something labeled R10.  But tha
t sounds like a 0.1 ohm resistor to me.  The output protected from over vol
tage by a TVS.  How exactly would that work?  Seems like the TVS would blow
 and then your tablet would blow.  

I haven't talked with my nephew about electronics since he was 8 and wanted
 me to help him build a robot.  lol  He's a PA in Houston now and works at  
Children's hospital where things are heating up from the virus.  This modul
e would require soldering.  If he hasn't done that before, he can learn now
.  Still, I just have no idea if these devices can be trusted.  Then there  
is no way to mount it other than tape.  

I also know nothing about what it takes to get the phone to draw an amp whi
le charging.  

I was going to add some USB power to the ash tray in my truck, but someone  
stole my truck and I may not replace it.  The car already has USB power con
nectors.  

I will book mark these guys.  Thanks.  

--  

  Rick C.

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Re: 12V to 5V conversion
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I haven't noticed any EMI, but I haven't been looking. they run at
hundereds of kiloherts so there probably are harmonics in the AM
broadcast band. the MLCCs on input and output probably help with that
more than the solid electrolytic capacitors do.


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Many of their other modules have their logo in the silkscreen. I don't
know if they have a dedicatred factory. I suspect their modules may be  
manufactured under contract.  It looks like the one in the photo has
the sticker over the logo.

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It might be that resistor, I don't know how to tell a fireproof
fusible resistor from a regular one without doing a destructive test.

there's something going on there as they've put an undersized
part on those pads.


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Epoxy works too. or heatshrink it in place. or a cable tie between the socket  
and the inductor... it may have been designed for a special enclosure  

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There is that. Apple had a different charger detection scheme to
android.  this module has the data pins shorted together,  I don't
know what an iPad will make of that. still a fixed tablet will
probably be fine with a 500mA charger as it will spend most of its
time attached to a working charger.  

--  
  Jasen.

Re: 12V to 5V conversion
Leaded flameproof resistors had a light blue body, when I was using them.

Re: 12V to 5V conversion
The transformer is in the attic to keep it from being disconnected. Either  
accidently, or on purpose. A fact that was difficult to teach to new instal
lers. "But the electricians installed an outlet right here!" Some friends f
actory was broken into. They cut the wires off every transformer to try to  
kill the alarm. They even pulled the electric meter before they gave up and
 fled.

Re: 12V to 5V conversion
On Saturday, July 11, 2020 at 8:27:12 AM UTC-4, Michael Terrell wrote:
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r accidently, or on purpose. A fact that was difficult to teach to new inst
allers. "But the electricians installed an outlet right here!" Some friends
 factory was broken into. They cut the wires off every transformer to try t
o kill the alarm. They even pulled the electric meter before they gave up a
nd fled.

The alarm has a battery as do nearly all such devices.  Cutting the power c
able is still easy since it has to come from the attic to the alarm panel.  
 Nothing about putting the power transformer in the attic makes it more tam
per resistant.  Nothing!  

Having the transformer in the attic makes it awkward to service.  I suppose
 it might be less likely to be unplugged when someone plugs in the vacuum c
leaner, but a sounder in the cabinet would remind them to put it back.  Tha
t's the typical way to alert people the power has been cut.  

The main reason I am not telling my nephew to ditch the alarm circuit board
 is because it contains a 12 volt UPS.  That's worth keeping.  

--  

  Rick C.

  ++ Get 1,000 miles of free Supercharging
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Re: 12V to 5V conversion
It was standard practice when i taught people to install alarms, in the '70s. What makes you think that a janitorial service cares what they leave unplugged?

Re: 12V to 5V conversion
.
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https://www.qskj.cc/shop/product/1941681-dc-dc-step-down-module-6-24v-12v-24v-to-5v-3a-power-supply-charger-qs-1205cbul-3a-79151?category26%64


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Re: 12V to 5V conversion
On Friday, July 10, 2020 at 3:03:06 PM UTC-7, Ricketty C wrote:
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is place for an alarm system.  The original panel is still there with 12 vo
lt power.  He is asking me about using that to mount an iPad with 5 volt po
wer.  We found various adapters...

Would you consider a vehicle-power USB charger?    Monoprice is usually
a good source, and you get a choice of USB-A or USB-C (or both).   And, rea
l
charging logic (required for the higher USB-C powers) beats a raw converter
 module.

Re: 12V to 5V conversion
On Friday, July 10, 2020 at 10:50:03 PM UTC-4, whit3rd wrote:
Quoted text here. Click to load it
 his place for an alarm system.  The original panel is still there with 12  
volt power.  He is asking me about using that to mount an iPad with 5 volt  
power.  We found various adapters...
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eal
er module.

The form factor is wrong.  There's no cigarette lighter socket... I mean po
wer interface socket to plug it into.  I'm looking for a box with the right
 words on the outside, the right electronics on the inside and four wires s
ticking out or terminals for connecting wires.  

Isn't that what you would want to shove in an electrical box in your house?
  I just don't want to recommend a 70 cent gadget if a $10 gadget is more l
ikely to work.  

--  

  Rick C.

  +- Get 1,000 miles of free Supercharging
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Re: 12V to 5V conversion
On Friday, July 10, 2020 at 10:37:15 PM UTC-7, Ricketty C wrote:
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power interface socket to plug it into.  I'm looking for a box with the rig
ht words on the outside, the right electronics on the inside and four wires
 sticking out or terminals for connecting wires.  

OK, those can be had as a car- motorcycle-upgrade item; howzabout this?

<https://www.banggood.com/12-24V-USB-Port-Car-Motorcycle-Power-Socket-Split
er-Charger-Adapter-p-954913.html>

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e?  I just don't want to recommend a 70 cent gadget if a $10 gadget is more
 likely to work.  

 The negotiation of power for anything other than 100 mA and/or 500 mA migh
t be  
a difficulty with a modern tablet; they just have to talk to the socket (an
d I'm not totally sure
how) before the real power flow starts.   Lightning/Thunderbolt and USB-3.1
 should accept
a goodly amount of power from the right kind of socket, but I've also seen  
cellphones that
wouldn't charge from a charger that lacked the right password (or resistor)
.

Modern USB-C 3.1 chargers aren't exactly 5V, even.   If they're happy with  
the handshake,
you can get 20V, 5A.

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