12V to 180V, help me stay safe, what is the proper V and W rating

[patbb]

Hello

I will try to build this tomorrow.

(pictures at the bottom but more info in the pdf)

this step the voltage up from 12V to 180V.

The pdf show all of the necessaty parts but unfortunately not the voltage and power rating of the components.


Anyone here have experience with this kind of device and would be willing to help me choose safe components?



Thank you very much!

 

[MikeMl]

Hi Pat. What do you expect this to do? It will deliver only a few mA at 170V, it will have rather poor voltage regulation, and be quite temperature sensitive. It is a rather poor attempt at building a step up converter...

 

[patbb]

Hi Mike, thank you for helping me out.


This is to power a few IN-9 Nixie tubes.
Hopefully will end up in a project box.

Do you think it's a bad solution?

I'm just getting started and beginning to experiment with electronics.
So I'm highly unexperienced and un-knowledgeable
if you have any better solution that won't break the bank, i will really appreciate any and all expert advices (and learning opportunities).


If you cannot think of anything better for my project, would you do me the favor of letting me know what power/voltage rating should i watch for in the circuirts i posted?

 

[MikeMl]

By your students, you will be taught.

I Googled IN-9 because I was not familiar with it. Here is what I found: https://tubehobby.com/datasheets/in9.pdf

Since that data sheet doesn't mention applications, I went looking for how to drive it to take advantage of its "bargraph" mode, and found this: https://www.die-wuestens.de/rd/IN9-2.pdf

This suggests to me that if the goal is to have a bargraph display, the +150V supply needs to be fairly well regulated, because the current though the IN-9 will be varying depending on how many segments are lit.

Most of the posted circuits just use an AC-line power supply using a conventional transformer. Is there a reason you are reluctant to do that?

 

[patbb]

Hi Mike!

Thanks again for your help!

The reason i don't use a AC-line power supply using a conventional transformer,
is because i wanted to try and build a VU meter and eventually a audio spectrum vizualizer with those things.
If i get the supply from an ac-line, then i will need 2 wires coming out of the project box no? would look interesting for sure but not what i want.

annnnd i wouldn't know how to setup the transformer to get what i want. I saw a few other thread were people suggested this but it seemed well above my current knowledge and ability.
I just searched around the web looking for power source for the thing and this kit is one of the very few that i found.
And the other ones were too complicated (one of them require to make my own transformer).

And i thought, if they sell this kit, it must be pretty decent no?



Anyway i built this circuit.
I manage to light up one of the tube (didn't try two).
(was a great pleasure to finally see the tube light up)
But the thing seem to be very weak and unreliable.
Without a load, voltage goes from 9V to 250V+ with 1/10 of a turn of the potentiometer.

Once the Tube is in place, it give about 135V maximum.


Still looking for a better solution to convert 12V into 150V+ in a cheap and better way.



Thank you!

 

[MikeMl]

Ok, but aren't you using some sort of AC power supply anyway to make the 12V to run the low-level circuits?

If you are working with audio, the last thing you want is to use the same 12VDC supply to power your audio circuits as will power the step-up converter. The converter input current is a square-wave which will be very hard to prevent from injecting noise into any other circuit that is powered from the same 12V.

As I said earlier, that step-up converter is a very primitive (naive) design. A proper step-up converter circuit is much more complicated, and uses some specialized components (inductor, catch diode, FETs, special IC) than a simple transformer, diode-bridge, filter capacitor, bleeder resistor analog brute-force power supply. The transformer based supply is much easier to build, especially for a novice.

The hardest thing about building the transformer based supply is obtaining the transformer. If I knew where in the world you were, I could suggest some sources for the transformer, including knowing the primary voltage (120V or 240V)?

 

[patbb]

Hi Mike,

Thank you very much again for the help.

>The transformer based supply is much easier to build, especially for a novice.
Now i start to be really interested!!
Maybe i should start to learn more about those.
After a quick google search, i failed to come up with any tutorials and or parts for a transformer that would do ac to 150+VDV.
If you don't mind, could you please point me in the right direction? what to look for?


I live in Toronto, Canada.

We have a few decent electronic stores around for parts. Not too many transformers but a few.


Thank you very much for the information!


Patrice

 

[patbb]

hello again.

One question, why do i need a transformer at all if i'm going to get 170V from the a/c?
Why not use a bridge rectifier right from the main a/c without a transformer?

Thank you!

What about something like this?
https://www.a1parts.com/transformers/Hammond_Power_Transformer_162_Series.htm
??

 

[MikeMl]

Ok Patrice, start by watching these three videos:

https://www.electro-tech-online.com/threads/power-supply-design-for-beginners.113613/

That will give you the basics.

Here is my idea: Get two identical small power transformers, like 120VAC to 24VAC with a center tap. Use the first to create a regulated 12VDC power supply as per the videos. Connect the second transformer backwards to the output of the first transformer, using the 24VAC side as the primary, and taking the output from the 120VAC winding. A simple diode-bridge (rated at 400Vpiv), a several hundred μF 200V electrolytic capacitor, and a bleeder resistor will get you about 150V at a few tens of mA.

 

[MikeMl]

One question, why do i need a transformer at all if i'm going to get 170V from the a/c?
Why not use a bridge rectifier right from the main a/c without a transformer?

Not safe. I do not like to see any hobbyist building "transformerless line-powered" anything...
The reason it is not safe is because the house circuit you are plugged into can supply 15 to 20A which is enough to cause a big explosion. Also, if the plug gets reversed such that what was Line becomes Neutral, and Neutral becomes Line, what you thought was the ground of your circuit becomes the hot side and vise versa. This could inadvertantly put 120Vac on the chassis of your project box, for example.

Using transformer isolation makes it so you can connect the ground side of your project to the green wire (fat prong), or to put it another way, both sides of the transformer primary circuit are completely isolated from your project box ground... Using a ~25W transformer also limits the short-circuit current that you can draw off the secondary due to core saturation in the transformer; a much smaller explosion

 

[patbb]

fantastic Mike, thank you!

one last question:

2 transformers 120VAC to 12VAC

the secondary of the first transformer goes to the secondary of the second transformer so that voltage goes back to 120VAC (I got that right yes?)

so can I also rectify the output of the first transformer to power the rest of the circuit?



Even if you don't answer this last question, i really want you to know that i appreciate your help!
I know this forum doesn't usually have lots of newbies and basic questions like this.


You are a rock star, thank you!

 

[MikeMl]

If I have some time tomorrow, I'll sketch something up. How much current do you want at 12V? Do you need -12V (split-supply for opamps)?

Go look on Flea-Bay for some transformers. Sometimes the ones you could use are called "24V control transformers". Look for something that is rated for ~1A of secondary current, more or less. Something like **broken link removed**.

Or possibly, find a plastic-encased wall-wart and bust off the plastic, like these.

 

[MikeMl]

Here is a single transformer that would work for you. By derating the VA, you could use one of the 115V Primaries as the real primary. Use the other to get your HV. Use the secondaries to get some combination of 12Vdc or +12Vdc and -12Vdc or +15Vdc and -15Vdc