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I wanted to discuss and ask questions about an old inverter circuit I built 15 years ago when I was studying; the circuit was powered with an ordinary 9 V battery-Duracell type, and steps the AC voltage up to 120 volts in 3 stages:
a 555, then an op amp and then a small audio transformer of 1:12.9 ratio from OEP oxford electronic products in UK.
The frequency it operated at was approximately 20 kHz.

I never loaded this circuit (I was learning (still am) and wanted to just understand the concept of AC and DC and see if I could build a circuit that operated close to mains voltage.)

(Sorry, I wont provide the circuit diagram, as I've described it above and is straightforward for your skill levels; instead I'll try post some files for your reference at bottom of this post.)

Let me first say please before I ask some questions: I am a learner-not a professional, so please treat my questions as electronic-noob skill level compared to you,-I'm trying to understand basic concepts.

  1. Does a high frequency (eg. 20 kHz) contain more 'energy' in it (and therefore current amplification)? Am I understanding this correctly?
  2. Could this circuit potentially be loaded and power anything useful (I understand not sensitive electronics as they depend on stable 50 Hz frequency)?
  3. If yes, I would like to power a boiling hot wort 6 W alcohol pump from it; can this be done?

https://www.kegland.com.au/products/replacement-brewzilla-35l-65l-6w-pump-magnetic-drive-pump-6-watt-fits-robobrew-3?_pos=14&_sid=fbda0b406&_ss=r

https://docs.rs-online.com/b006/0900766b810fb25c.pdf

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    \$\begingroup\$ 6W from 9V battery is too much. Also it will be drained in 1 hour. \$\endgroup\$ Commented Jul 14, 2023 at 3:58
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    \$\begingroup\$ You are looking at 6 D alkaline cells to give you a few hours worth of use (maybe a little under 6 or so, quick glance at datasheet.) A 9 V alkaline can't even begin to do the job. Are you asking what a 9 V can power at 120 V? \$\endgroup\$ Commented Jul 14, 2023 at 4:30
  • \$\begingroup\$ Thank you for these responses which are useful regarding power consumption. \$\endgroup\$ Commented Jul 14, 2023 at 5:09
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    \$\begingroup\$ You can get 9 volt batteries in the UK (called PP9) that are quite big and can supply decent current @MichalPodmanický \$\endgroup\$ Commented Jul 14, 2023 at 8:52

2 Answers 2

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The transformer you linked is intended for low energy, medium-high impedance audio circuits, not for any kind of power application. The output voltage of your circuit will decrease significantly with only a few mA of load current.

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  1. Not really. Small transformers work better at high frequencies. Low frequencies (50 to 60Hz) require heavy iron-cored transformers.
  2. The amount of power you'll be able to draw will be very limited. The transformer specified has a very high resistance. The chances are that an ordinary opamp (as distinct from an audio power amplifier) won't be able to deliver the power you need either.
  3. Probably not, given the comments for 2. But that's a 220-240V 50/60Hz pump in your link, not 120V 20kHz.
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