12v DC to 24v 50Hz AC square-wave 500mA: transformer & transistor?

[NeverEtched]

'All I want to do' is take a 12v DC input and convert that to 24v AC (50Hz square-wave 500mA).

I'm currently thinking of making a two-transistor DC to AC converter, and then using a chassis transformer to double the 12v AC to 24v AC. Simple, eh?

Given that I reckon a max 500mA load, can (will) anyone please specify a transistor (ideally known in the UK) suitable to the above; and could (would) someone kindly end my shame by telling me what such a 1:2 transformer is known as in the business, and ideally, what spec would be appropriate?

Thank you

 

[Bluejets]

555 and an up converter
mosfet on the 555 output

 

[WHONOES]

What are you hoping to use it for?

 

[NeverEtched]

Thanks to Bluejets and WHONOES.
Bit too succinct for me, Bluejets , I can read a circuit diagram and know which end of a soldering iron to avoid, but I'd need to search out how to connect the 555 (timer chip?).
WHONOES: I have a 12v solar set-up in the back garden, to which I want to add static* led string lights, but the only suitable length (for outdoor use) of lights I've found (*i.e. which does not include a timer function or flashing modes), it turns out to my surprise, runs on 24v AC @50Hz.
Hence wanting to get from12v DC to 24 AC, at <500mA.
I've seen circuit diagrams for 12v DC to 12v AC, which I was going to use with a 1:2 chassis transformer, but evidently I don't know what search terms to use to find a suitable transformer, which always seem to lead to 12v DC to 24v DC converters: I want 12v DC to 24v AC.
So I was after the search term for the transformer, and guidance on a suitable mosfet. But any help or info will be appreciated!

 

[WHONOES]

If you are using it to run some LED's then you should be OK with a d.c. supply. LED strings that run on 12V d.c. are available.
Can you provide a link to the LED string you are proposing to use?

 

[NeverEtched]

Thanks WHONOES
I've ordered a 12v DC to 24v DC converter to check out whether 24v DC will do the trick (should be here tomorrow), and will report back.
There's no useful tech info about the LED string. I bought it as a decent length static outdoor string, complete with mains transformer, which I removed and checked the voltage and polarity. I wasn't expecting the 24v AC thing...
You'd think it would be easy to find a decent length (10m+) 12v DC outdoor static led string that doesn't have a mode controller (flashing) or timer. If you can find one (available in the UK), you'll be doing better than I! Almost all have a 'mode' controller.
Flashing mode led strings tend to work (afaik) by switching psu polarity, so alternate leds light, which means of course that with a straight dc supply only half will light. The 'all on' option I think is achieved by rapidly switching psu polarity, giving the illusion of being constantly on.

 

[NeverEtched]

After I wrote the above I remembered* I'd already bought a 12v DC to 24v DC converter, and it doesn't work (*but not before I'd ordered another one ). Some lights dimly glow, and that's it. The 'why' is curious, but I'm just after a practicality here.

So, can I get back to my original request... I need to go from 12v DC to 24v AC. I am intending to do this by using a simple circuit, as in this youtube video, and use a transformer to boost the output to 24v (50Hz square-wave <500mA). If this is workable, then:

What I want to know is can anyone identify a suitable (pair of) transistors/mosfets? The video shows a ctc1351, but I can't find that for sale (in the UK), or indeed much basic info.

I would also appreciate guidance as to specification of a suitable chassis transformer, or the specification I should search on, for a 1:2 step-up transformer (on the supposition there is such an item). I'm getting nowhere with my searches.

Thanks!

 

[Martaine2005]

I think you need to go back to the drawing board.
What current does your solar panel supply? Or what solar setup have you got?.
What was the output current on the supplied AC adapter? (not input). Specs from the label.
What are the specs of the DC to DC converter you tried?
Are there any other components inside the adapter? Bridge rectifier? Diodes? capacitors?
How long is the LED string?
How many LEDs in total?

Martin

 

[NeverEtched]

Thanks for taking an interest, Martaine2005.

The solar array is irrelevant: as far as this is concerned, it's effectively a 12v battery (in fact 4x big lead-acids: I mentioned the solar power solely to indicate that it's for a self-powered outdoor set-up, not mains).
The original adapter output is 150mA, 3.6VA (I want to power 2 strings with my converter, hence my <500mA).
The DC-DC converter is 9-20v input, 24v 5A output.
I have no idea what components are in the original adapter and the DC-DC converter, both are sealed units.
80 LEDs, 12.8m (+10m to original adapter) length.

Are you saying that what I propose will not work?

Is what I am asking impossible? If the youtuber's circuit will not work, or there is no suitable transistor/mosfet alternative to his ctc1351, or 1:2 chassis transformers do not exist, please say so.

Otherwise, as per my original enquiry, what transistors/mosfets could I use instead of a CTC1351 (on sale in the UK), and what term / specification should I search on, for a 1:2 step-up chassis transformer?

 

[NeverEtched]

Sorted. Well-advised on a different electronics forum.
Going for a 100w (my choice) 12v dc to 240v ac inverter, and a 240v to 24v transformer. (I tested the led lights with the transformer on a 300w inverter.)