quantum Posted July 25, 2004 Report Share Posted July 25, 2004 Would it be possible to switch a transformer that is made to transform down, and make 120 volts from 9 volts? Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted July 25, 2004 Report Share Posted July 25, 2004 The switching power supply would take the 9volt supply and switch the input from 0 to 9. The step down would take this and reduce it. So no. Remember also that the 9volts has to be directly on the transformer without a resistor. A resistor would turn it into an LR circuit which would create a negative transient when the pulse goes high caused by the tranisistor going into cutoff. Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted July 25, 2004 Report Share Posted July 25, 2004 Yes if the supply voltage is AC not DC. I have used 24 vac to get 220vac this way Also 120v input and I got 240v out.DC will not work unless you pulse it and send it thru. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted July 26, 2004 Report Share Posted July 26, 2004 Hotwaterwizard, how do expect to get 220v from a 9v without a stepup transformer. Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 28, 2004 Report Share Posted July 28, 2004 Quantum,Inverters use a transformer "connected backwards" to step-up a low AC voltage to 120VAC. The low-voltage winding is usually center-tapped to keep the driving circuitry simple, and the output is square-wave instead of sine-wave. The driving circuitry is an oscillator with opposing outputs. Since power output equals almost as much as power input, a 9V battery won't supply much 120VAC power for much time. Quote Link to comment Share on other sites More sharing options...
quantum Posted July 28, 2004 Author Report Share Posted July 28, 2004 Audioguru, are you saying that the 9 volt battery will be drained much quickly? How 'bout if you put at least three 9 volt batteries parallel, having thrice as much current.I have a feeling that all this depends on the consumer prefrence.How 'bout switching the 9 volt battery with cigaret lighter in a car. Would that mess the project bases up? Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 28, 2004 Report Share Posted July 28, 2004 Quantum,3 paralleled little 9V batteries are good for only about 60mA. Therefore their power output is only about 1/2 Watt. The inverter will have some loss, so its output power will be less. If you power it from a car battery, then its output voltage will be too high, but it will still be limited to the power ratings of its transformer and transistors.What do you have that needs only about 1/3 Watt from 120VAC?If you use a bigger, more powerful transformer and big, heatsinked multiple transistors, then you can get more power from it using a car battery to power it. Quote Link to comment Share on other sites More sharing options...
quantum Posted July 28, 2004 Author Report Share Posted July 28, 2004 1. First off audioguru, how do you use the stubborn "quote" icon?2. How did you come up with 60mA? Where is the resistance? Hmmm.3. Who sayed that I neened 1/3 Watt of power?4. I have no intention to build this project (although it would be useful) at this present time. I am just simply theoretically building it. Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 29, 2004 Report Share Posted July 29, 2004 Hi Quantum,I'll try to answer your questios:1) To reply with a quote, login, then click Quote on the reply that you want to be quoted.Delete what you don't want, then reply below the quote.2) For battery current/life, I looked at a battery manufacturer's datasheets. For a 6.0V end voltage, a little 9V carbon-zinc battery will supply 20mA for 15 hours. A little 9V alkaline battery will do the same for 30 hours. The alkaline will supply 500mA for only about 18 minutes. The graphs shows different end voltages and you can select any current. Look at the "technical info" on this website:www.energizer.com3) 60mA from 9V (1/2 Watt) into an inverter will supply only about 1/3 Watt at 120VAC. 84 Amps from a 12V car battery into an inverter will supply about 1000 Watts for about 75 minutes. 4) Look at the lithium and NI-MH batteries on the website. They last a long time. Quote Link to comment Share on other sites More sharing options...
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