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| 12v DC to 12V AC |
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| .....:
i am building and amp project where the preamps need 12v ac and everything else needs 12v dc is there any cheap way for me to convert the 12vDC to the 12vAC required fro the amplifiers i have some 12vDC to 110V DC el wire inverters that i could use to get the power to AC but i dont know how to get it back down to 12V. Jack |
| Ian.M:
No. The odds are the diodes in the preamp PSUs aren't suitable for HF use so you cant simply chop it into a squarewave at >30KHz, + the AC supply may need one side ground referenced, so you cant drive it as a bridge tied load from a H bridge to get the negative half cycles. You also cant generate a 50Hz 12V RMS sinewave to keep the diodes happy as that would need 17V supply rails to get the peak voltage. Therefore you'll need an inverter circuit with a transformer. You cant easily get a self-oscillating resonant Royer ciruit to work at such a low frequency so will need a full inverter controller. It would be much easier to hack the preamps to use + and - DC in & Gnd, then use a boost converter to get 16V to feed their + rail and an inverting buck converter to feed their - rail with 16V (assuming approx 1V of diode drop in their existing PSU circuit). |
| .....:
thanks for the reply how would i go about converting the preamp to run on dc power instead of ac jack |
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here is a link to the page that i bought the preamp from there is a picture of the unpopulated board on picture 6 https://www.ebay.co.uk/itm/AC-12V-6J1-Valve-Pre-amp-Tube-PreAmplifier-Board-Headphone-Amplifier-Case/292651946401?ssPageName=STRK%3AMEBIDX%3AIT&var=591452656946&_trksid=p2057872.m2749.l2649 jack |
| ArthurDent:
If you don't need this to run free of mains power the simpler thing would be to first use a mains to 12VAC transformer for the preamps then next rectify/filter the transformer output to also get 12VDC, or use a seperate 12VDC supply. You may need a regulator as well to stabilize the 12VDC but without knowing more about the application no one can guess. Using the EL drivers are not a good idea. |
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