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Dual Offest Sub-audio Test Signal

Started by Unknown May 23, 2014
"David Eather"
>> Phil Allison >>
( big snip)
> ** Harrison ( editor of ETI magazine in the 1980s) was a ham radio > ru - so knew little about electronics .... > > He was obliged to trust contributors and staff alike, having no way nor > much interest in seeing through the smoke and mirrors game that was going > on. > There were a number of front page projects that simply did not work, but > he was not interested in hearing about any of them nor the scam "TIC" > brand, > fake MJ15003/4 power transistors that DSE had imported thousands of. > > > I remember them. I had a job at DSE and they sent around memos (and a > weekly video) claiming they were all kosher but a lot of people knew the > truth.
** Just in case any of the regulars think "TIC" = Texas Instrument Corporation - in this case, it does not. The initials stood for the "Transistor Instrument Co." of Florida. A 100% scam business whose only expertise was screen printing new numbers and logos on reject and discarded TO3 devices. FYI: when tested, most of the devices marked " TIC" and "MJ15003/4 " turned out to be high voltage switches or power Darlingtons. .... Phil
On Sunday, May 25, 2014 5:37:18 PM UTC-4, jgil...@netscan.com wrote:
> On Sun, 25 May 2014 03:23:49 -0500, John Fields > > <jfields@austininstruments.com> wrote: > > > > > > >I'm late into the fray. > > > > > >Is your supply's output: +6V 0V -6V or is it lacking a common? > > > > > > > Hello John. To achieve the waveforms shown below, I believe the coils > > cannot be ground referenced. Maybe I am wrong, but so far I do not see > > any other suggestion that would do this. > > > > http://www.4shared.com/download/Z_6zeE2yce/dual_dc_offset.jpg?lgfp=3000 > > > > I know this is not a conventional design, however some viewers have > > kindly sent in circuits that appear to address the problem, and > > correct my own flawed attempts. > > > > https://dl.dropboxusercontent.com/u/16764432/SED_JG_MAY14_a1.pdf > > > > http://www.digikey.com/schemeit/#u7g > > > > I know you are one of the long-time "experts" here, so if you have any > > comments they would be most appreciated. > > > > John Gallimore
Hi John G, So have you got this working yet? I might try something like this. (I'm an opamp type of guy.) https://www.dropbox.com/s/u8684izdbylf68a/DSCF0019.JPG The TCA0372's should be fine at your required ~100mA. You'd make the +/- 4 volts from resistor dividers or reference's depending on how stable you wanted them. Can you tell us what this is for? George h.