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HELP!! TRANSFORMLESS power supply

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The zener sets the output voltage. Its just 4 one watt 10 or 12 volt diodes in series.
Just use what combination of zener diodes you need to get the right voltage you want. Three 12's would give you 36 volts too.

R1 is needed but R2 is optional.
I never use R2 in any of my power supplies like this. I just add it so the electrophiles dont ***** too much when ever I post a schematic like this.

For an AC output just pull power off the AC side of the rectifiers and use the DC side as the voltage regulator. C2 can be reduced by a factor of ten for that type of application. Depending on the load the zener diodes may need to be changed to higher voltage values though.
 
The zener sets the output voltage. Its just 4 one watt 10 or 12 volt diodes in series.
Just use what combination of zener diodes you need to get the right voltage you want. Three 12's would give you 36 volts too.

R1 is needed but R2 is optional.
I never use R2 in any of my power supplies like this. I just add it so the electrophiles dont ***** too much when ever I post a schematic like this.

For an AC output just pull power off the AC side of the rectifiers and use the DC side as the voltage regulator. C2 can be reduced by a factor of ten for that type of application. Depending on the load the zener diodes may need to be changed to higher voltage values though.

Thank You.... I hate to show my stupidity but, I have to ask. You wrote "For an AC output just pull power off the AC side of the rectifiers and use the DC side as the voltage regulator". First of all, taht totally confused me, I acknowledge that I'm a newbee but, please explain to me where I can pull off an AC changed voltage before the rectifiers (diodes). Aren't all / both lines of the circuit AC in (line voltage). Where do I get a reduced AC voltage? Also (sorry for all the questions, especially when you have already been so helpful), what do you mean "use the DC side as the voltage regulator? Sorry but, I'm just not seeing the regulator either. I'm sure it's me but, any help would be appreciated.
 
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The whole point to using a capacitive supply is reduced cost and size with a 30uf motor start capacitor this isn’t the case.

That 30uf Cap won’t be cheap or small. I did find a non-ROHS compliant one for $4.99 though here.

**broken link removed**

Usually they are in the $15.00 dollar and up range also note the size. You can buy a pre made PSU isolated for that price at your power range (30W).

The most economical and smallest solution is an offline buck using an NCP12 series controller The controllers with an integrated switch that I know of cant handle that power but the NCP12 series uses an external switch. See the application note below for more information.

https://www.intusoft.com/onsemipdfs/and8078.rev0.pdf

30 cents for a NCP1203

**broken link removed**

Inductor $1.3 (You could probably find a cheaper one)

BOURNS|SRR1806-102M|Inductor | Newark Canada

mosfet $0.58

FAIRCHILD SEMICONDUCTOR|FQP5N50C|MOSFET | Newark Canada

And a few other components
 
The whole point to using a capacitive supply is reduced cost and size with a 30uf motor start capacitor this isn’t the case.

That 30uf Cap won’t be cheap or small. I did find a non-ROHS compliant one for $4.99 though here.

**broken link removed**

Usually they are in the $15.00 dollar and up range also note the size. You can buy a pre made PSU isolated for that price at your power range (30W).

The most economical and smallest solution is an offline buck using an NCP12 series controller The controllers with an integrated switch that I know of cant handle that power but the NCP12 series uses an external switch. See the application note below for more information.

https://www.intusoft.com/onsemipdfs/and8078.rev0.pdf

30 cents for a NCP1203

**broken link removed**

Inductor $1.3 (You could probably find a cheaper one)

BOURNS|SRR1806-102M|Inductor | Newark Canada

mosfet $0.58

FAIRCHILD SEMICONDUCTOR|FQP5N50C|MOSFET | Newark Canada

And a few other components


Huh? I don't need to operate a motor, I'm driving 4 transducers. I always appreciate help and information on the locating of parts. I guess I don't understand what these parts have to do with the SMPS I was refering to.
 
Huh? I don't need to operate a motor, I'm driving 4 transducers.

Read the description of the capacitor I linked to.

“Capacitor Type:Motor Start/Motor Run”

Those are the types of capacitors you would be using at such a high capacitance and AC voltage they are called “Motor Start”. If anyone has a line on cheaper ones I’d be interested.


I guess I don't understand what these parts have to do with the SMPS I was refering to.

It has to do a lot with the SMPS you were talking about.The NCP1203 is a SMPS controller which can be used to construct a non-isolated BUCK (Step down converter). The components I linked to are possible candidates for the power stage.
 
Size and cost are relative to the person. I find a 30 uf 370 volt AC capacitor small by the standards I work with.

Here is the ones like I have. Its about 3 inches long and about 1.5 inches in diameter. $5 on eBay.

I have no clue how to get linking to work so here is the eBay listing title.
Air Compressor Motor Capacitor 30 UF 370 Vac 50/60HZ


Motor run and power factor correction are just capacitor terminology related to there most common applications they are used in.

Just build it. It works. :D If you over analyze it too much you will get a headache and ask to many questions and then some one will talk you into something else more expensive and harder to build. ;)
 
ust build it. It works. :D If you over analyze it too much you will get a headache and ask to many questions and then some one will talk you into something else more expensive and harder to build. ;)

Yes my response to the OP’s question is more complicated particularly for someone with little experience but he did ask about SMPS’s.
Here is the ones like I have. Its about 3 inches long and about 1.5 inches in diameter. $5 on eBay.

I have no clue how to get linking to work so here is the eBay listing title.
Air Compressor Motor Capacitor 30 UF 370 Vac 50/60HZ

I’ve built several of both PSU’S non isolated SMPS’s and capacitive. From my experience a capacitive psu becomes too large and more costly over about 70mA then a non-isolated SMPS. The same power supply could fit comfortably on your (1.5'' x 3") 30uf cap with room to spare using the NCP1203. The whole smps would be cheaper then the 5 dollar cap too.

I don’t buy components from ebay. To much bogus parts and other BS.

I wasn’t disputing that it would work so would a 50W resistor and a zener (shunt) it’s just not the most economical solution or what I would consider practical solution. Anybody who is considering building a non-isolated power supply I assume cost/size is important or they would just either purchase a transformer for SMPS or Linear regulator. Or just buy a PSU ready made.
 
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I just give ideas. Ultimately its up to the person what they want. I personally would have went with the original transformers from the earlier thread myself.
Over analysis with out proper knowledge wastes a lot of time effort and money.
It often finds problems that dont exist based on observations that dont merit any actual real concerns.

Hence my statement, Just build it. It works.

I have never had problems buying form eBay, but then thats what the seller rating system is for.
If they are a store with a low transaction number and a fairly high bad reputation ratio I dont buy from them.
Same with new sellers. If they dont have a rating over 100 but have a 100% for what they have sold I will trust them.

I sell on eBay from time to time and I have had several buyers that were not happy just because I sold them exactly what they saw and read in the description.
A broken and possibly unrepairable device intended for parts salvage only with an as is sales condition cheap!
Or they simply had no understanding of what they were buying. If you need a MIG welder why bid a plasma cutter up high just because they both plug into 230 volts and work with metal. Not my fault.
eBay backed me up on both situations with outstanding help.
 
i use it for my router adapter that need 3.3v 2A
i have 2 part of the circuit 1st part is the rectifier part and 2nd part is my lm317 regulator part

So I assuming your router has at least one Ethernet cable stringing out for a internet connection and possibly more for computers.

I know that Ethernet uses differential signaling but could having the supply to this router non-isolated cause havoc on other connected devices?

~Tyler
 
Ethernet cables are transformer isolated on both ends, it's part of the electrical standard.
 
Actually POE devices (at least 802.3af-2003) are based on ~48VDC. Powered devices are going to have a simply switching supply to adjust it to the required level. The standards are still in flux, but if it says POE on the box it's likely the 802.3 standard. If you've actually seen AC powered POE equipment it's not standardized, or at least not one that I know of.
 
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