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LF: Re: off topics: Inverter 12V/-12V wanted from DK 8 ND

To: [email protected]
Subject: LF: Re: off topics: Inverter 12V/-12V wanted from DK 8 ND
From: "Dave Brown" <[email protected]>
Date: Fri, 27 May 2005 09:15:59 +1200
Delivery-date: Thu, 26 May 2005 22:16:23 +0100
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There used to be a low frequency arrangement using a 555 timer as a DC-DC converter for charging NICds from a 12 volt supply-was common in the amateur literature maybe 20 years ago. Might be the sort of thing to use? Just googled and this looks like the sort of thing I mean.
http://ourworld.compuserve.com/homepages/Bill_Bowden/page10.htm#5volts.gif

73
Dave, ZL3FJ

----- Original Message ----- From: "Hans-Albrecht Haffa" <[email protected]>
To: <[email protected]>
Sent: Friday, May 27, 2005 2:45 AM
Subject: LF: off topics: Inverter 12V/-12V wanted from DK 8 ND


Dear Lowfers,
for a cw-shaping circuit with an op-amp (second order key-klick filter by Jim Moritz) I need an inverter for the negative supply of the op-amp. It is not possible to choose an dc/dc-converter, as most of these devices operate at frequencies of 100 kHz...500 kHz, just where the receiver will run. So it is necessary to design an inverter with an transformer running at 100 Hz...500 Hz, what is a good frequency for laminated cores designed for 50 Hz ac. Effectivity may be low, as the circuit will draw only a few mA at voltages of -5...-12V, when powered at +12V. My current thought: Astable multivib followed by driver-transistor and an 230V/12V-12V-Transformer (the 230V ac-windign will not be used). After rectification and stabilisation an voltage of -4V...-6V seems to be feasable. Have You already done somthing similar? Any proposals warmly welcome.
55, Hans-Albrecht
DK 8 ND           cba




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