Forums

Opamp power supply

Started by amdx December 3, 2015
Hi all,
I'm about to build this detector/audio amp circuit.

> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm
I want to run it from batteries, I thought it was +/- 4.4v supply. I thought I was going to use 6 AA cells and center tap them, but maybe not. I just noticed it looks like it's +12 and -4.4v. First, does that make sense? Or could it be an error in the presentation. See figure 2 and 1 for Power supply connections. Any other thoughts about the circuit? Thanks, Mikek
On Thu, 3 Dec 2015 16:20:37 -0600, amdx <nojunk@knology.net> wrote:

>Hi all, >I'm about to build this detector/audio amp circuit. > >> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm > >I want to run it from batteries, I thought it was +/- 4.4v supply. >I thought I was going to use 6 AA cells and center tap them, > >but maybe not. >I just noticed it looks like it's +12 and -4.4v. > First, does that make sense? Or could it be an error in the >presentation. See figure 2 and 1 for Power supply connections. > >Any other thoughts about the circuit? > > Thanks, Mikek >
Looks like a great noise generator. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 12/3/2015 5:28 PM, John Larkin wrote:
> On Thu, 3 Dec 2015 16:20:37 -0600, amdx <nojunk@knology.net> wrote: > >> Hi all, >> I'm about to build this detector/audio amp circuit. >> >>> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm >> >> I want to run it from batteries, I thought it was +/- 4.4v supply. >> I thought I was going to use 6 AA cells and center tap them, >> >> but maybe not. >> I just noticed it looks like it's +12 and -4.4v. >> First, does that make sense? Or could it be an error in the >> presentation. See figure 2 and 1 for Power supply connections. >> >> Any other thoughts about the circuit? >> >> Thanks, Mikek >> > > Looks like a great noise generator. > >
I'm not surprised to hear a negative critique. I built the amp he designed, and when I had a question, I got all kinds of remarks about what was wrong with it and that it didn't meet his specs. Ok, so what would you do different for the detector? All I want to do is drive a meter to compare ferrite L/C antennas. Since I have a high impedance amp with 50 ohms out, I could use a low input impedance detector. But either way. 550kHz to 1700kHz range needed, wider is better. The audio part is a useful bonus. Mikek
On Thursday, 3 December 2015 22:20:45 UTC, amdx  wrote:
> Hi all, > I'm about to build this detector/audio amp circuit. > > > http://www.crystal-radio.eu/diodedetector/endiodedetector.htm > > I want to run it from batteries, I thought it was +/- 4.4v supply. > I thought I was going to use 6 AA cells and center tap them, > > but maybe not. > I just noticed it looks like it's +12 and -4.4v. > First, does that make sense? Or could it be an error in the > presentation. See figure 2 and 1 for Power supply connections. > > Any other thoughts about the circuit? > > Thanks, Mikek
Opamp driving a transformer... very 70s. IC used to generate -ve rail when the input could just have been divided or rectified both ways... why? NT
On Thu, 3 Dec 2015 19:07:23 -0600, amdx <nojunk@knology.net> wrote:

>On 12/3/2015 5:28 PM, John Larkin wrote: >> On Thu, 3 Dec 2015 16:20:37 -0600, amdx <nojunk@knology.net> wrote: >> >>> Hi all, >>> I'm about to build this detector/audio amp circuit. >>> >>>> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm >>> >>> I want to run it from batteries, I thought it was +/- 4.4v supply. >>> I thought I was going to use 6 AA cells and center tap them, >>> >>> but maybe not. >>> I just noticed it looks like it's +12 and -4.4v. >>> First, does that make sense? Or could it be an error in the >>> presentation. See figure 2 and 1 for Power supply connections. >>> >>> Any other thoughts about the circuit? >>> >>> Thanks, Mikek >>> >> >> Looks like a great noise generator. >> >> > > I'm not surprised to hear a negative critique. >I built the amp he designed, and when I had a question, >I got all kinds of remarks about what was wrong with it and >that it didn't meet his specs. > > Ok, so what would you do different for the detector?
I'd hook your antenna directly to an oscilloscope. Maybe with a jfet follower if you care much about capacitive loading.
On 12/3/2015 8:36 PM, tabbypurr@gmail.com wrote:
> On Thursday, 3 December 2015 22:20:45 UTC, amdx wrote: >> Hi all, >> I'm about to build this detector/audio amp circuit. >> >>> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm >> >> I want to run it from batteries, I thought it was +/- 4.4v supply. >> I thought I was going to use 6 AA cells and center tap them, >> >> but maybe not. >> I just noticed it looks like it's +12 and -4.4v. >> First, does that make sense? Or could it be an error in the >> presentation. See figure 2 and 1 for Power supply connections. >> >> Any other thoughts about the circuit? >> >> Thanks, Mikek > > Opamp driving a transformer... very 70s.
I plan on using the Radio Shack 1000 ohm to 8 ohm transformer, I think I have one around here.
> IC used to generate -ve rail when the input could just have been divided or rectified both ways... why? > > > NT >
I don't know, post a quick schematic so I can see what you mean. Thanks, Mikek
On 12/3/2015 5:28 PM, John Larkin wrote:
> On Thu, 3 Dec 2015 16:20:37 -0600, amdx <nojunk@knology.net> wrote: > >> Hi all, >> I'm about to build this detector/audio amp circuit. >> >>> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm >> >> I want to run it from batteries, I thought it was +/- 4.4v supply. >> I thought I was going to use 6 AA cells and center tap them, >> >> but maybe not. >> I just noticed it looks like it's +12 and -4.4v. >> First, does that make sense? Or could it be an error in the >> presentation. See figure 2 and 1 for Power supply connections. >> >> Any other thoughts about the circuit? >> >> Thanks, Mikek >> > > Looks like a great noise generator. > >
Is that from the opamp or the circuit design?
On 12/3/2015 8:45 PM, John Larkin wrote:
> On Thu, 3 Dec 2015 19:07:23 -0600, amdx <nojunk@knology.net> wrote: > >> On 12/3/2015 5:28 PM, John Larkin wrote: >>> On Thu, 3 Dec 2015 16:20:37 -0600, amdx <nojunk@knology.net> wrote: >>> >>>> Hi all, >>>> I'm about to build this detector/audio amp circuit. >>>> >>>>> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm >>>> >>>> I want to run it from batteries, I thought it was +/- 4.4v supply. >>>> I thought I was going to use 6 AA cells and center tap them, >>>> >>>> but maybe not. >>>> I just noticed it looks like it's +12 and -4.4v. >>>> First, does that make sense? Or could it be an error in the >>>> presentation. See figure 2 and 1 for Power supply connections. >>>> >>>> Any other thoughts about the circuit? >>>> >>>> Thanks, Mikek >>>> >>> >>> Looks like a great noise generator. >>> >>> >> >> I'm not surprised to hear a negative critique. >> I built the amp he designed, and when I had a question, >> I got all kinds of remarks about what was wrong with it and >> that it didn't meet his specs. >> >> Ok, so what would you do different for the detector? > > I'd hook your antenna directly to an oscilloscope. Maybe with a jfet > follower if you care much about capacitive loading. > >
I want it battery operated, so I can setup in the backyard away from noise sources and read an analog meter. I'd like as little loading as possible which I think I have, with the Kleijer amp I previously built. This can be my impedance converter very high input to 50 ohms output. Thanks, Mikek
On Friday, 4 December 2015 12:22:00 UTC, amdx  wrote:
> On 12/3/2015 8:36 PM, nt wrote: > > On Thursday, 3 December 2015 22:20:45 UTC, amdx wrote: > >> Hi all, > >> I'm about to build this detector/audio amp circuit. > >> > >>> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm > >> > >> I want to run it from batteries, I thought it was +/- 4.4v supply. > >> I thought I was going to use 6 AA cells and center tap them, > >> > >> but maybe not. > >> I just noticed it looks like it's +12 and -4.4v. > >> First, does that make sense? Or could it be an error in the > >> presentation. See figure 2 and 1 for Power supply connections. > >> > >> Any other thoughts about the circuit? > >> > >> Thanks, Mikek > > > > Opamp driving a transformer... very 70s. > > I plan on using the Radio Shack 1000 ohm to 8 ohm transformer, I think > I have one around here. > > > IC used to generate -ve rail when the input could just have been divided or rectified both ways... why?
> I don't know, post a quick schematic so I can see what you mean.
the former: o----------Reg------o +out | | dc in +-------o 0v | | o----------Reg------o -out the latter, from ac in: http://www.seventransistorlabs.com/tmoranwms/Circuits_2008/Rectifier_Tutorial.gif Bottom left for half wave version But if you're running from battery, why not just tap the battery? It's a fair few cells, but they'll last longer due to lower current draw. NT
On Fri, 4 Dec 2015 06:29:00 -0600, amdx <nojunk@knology.net> wrote:

>On 12/3/2015 8:45 PM, John Larkin wrote: >> On Thu, 3 Dec 2015 19:07:23 -0600, amdx <nojunk@knology.net> wrote: >> >>> On 12/3/2015 5:28 PM, John Larkin wrote: >>>> On Thu, 3 Dec 2015 16:20:37 -0600, amdx <nojunk@knology.net> wrote: >>>> >>>>> Hi all, >>>>> I'm about to build this detector/audio amp circuit. >>>>> >>>>>> http://www.crystal-radio.eu/diodedetector/endiodedetector.htm >>>>> >>>>> I want to run it from batteries, I thought it was +/- 4.4v supply. >>>>> I thought I was going to use 6 AA cells and center tap them, >>>>> >>>>> but maybe not. >>>>> I just noticed it looks like it's +12 and -4.4v. >>>>> First, does that make sense? Or could it be an error in the >>>>> presentation. See figure 2 and 1 for Power supply connections. >>>>> >>>>> Any other thoughts about the circuit? >>>>> >>>>> Thanks, Mikek >>>>> >>>> >>>> Looks like a great noise generator. >>>> >>>> >>> >>> I'm not surprised to hear a negative critique. >>> I built the amp he designed, and when I had a question, >>> I got all kinds of remarks about what was wrong with it and >>> that it didn't meet his specs. >>> >>> Ok, so what would you do different for the detector? >> >> I'd hook your antenna directly to an oscilloscope. Maybe with a jfet >> follower if you care much about capacitive loading. >> >> > >I want it battery operated, so I can setup in the backyard away from >noise sources and read an analog meter. > I'd like as little loading as possible which I think I have, with the >Kleijer amp I previously built. This can be my impedance converter very >high input to 50 ohms output. > > Thanks, Mikek >
A front-end diode rectifier, a crystal set, will be a very nonlinear detector, with a bad temperature coefficient. You might amplify up to some decent signal level, and then rectify. Pop in attenuators as needed. Several people make really cool integrated, wide-range, log-output RF detector chips, with all the hard work done. ADI, LTC, maybe TI. Talk someone out of an eval board.