Unusual functions of cheap parts

Don't forget the LED as an low-noise zener diode with integrated function control. Some high-fidelity enthusiasts use this in good audio amplifiers.

- Henry

"ehsjr" schrieb im Newsbeitrag news:R3thf.9922$BU2.983@trndny01...

diode,

diode.

another

some

There even exists LED specially taylored to the needs of doing duplex operation.

- Henry

"Frithiof Andreas Jensen" schrieb im Newsbeitrag news:dm6msq$bvk$ snipped-for-privacy@news.al.sw.ericsson.se...

light

yield

LED.

Bob Pease of National Semi mentioned a ONE AND ONLY transistor circuit above/under voltage rail converter (with detailed theory). I cannot remember the details. But interesting if sometime a slightly voltage behind the power rail is needed. For example to power a CMOS Opamp now doing rail-input.

- Henry

Yes Martin. I've seen that and a refrigerator can it too!

- Henry

"martin griffith" schrieb im Newsbeitrag news: snipped-for-privacy@4ax.com...

diode,

another

Can you give details?

- Henry

"John Larkin" schrieb im Newsbeitrag news: snipped-for-privacy@4ax.com...

Am 25 Nov 2005 06:28:21 -0800 schrieb :

At least the audio amp, this is nice to build with some Inverters (4069) with resistive Feedback.

Am Fri, 25 Nov 2005 22:13:38 -0500 schrieb Phil Hobbs :

An electric arc with just 3V from two D-cells? I thought the arc needs at lesat 20V burning voltage.

Am Sat, 26 Nov 2005 16:16:27 +0000 (UTC) schrieb Matthias Weingart :

But how to decide to switch it off? I think there you have to sample - switch of for a short time and test. This could give a flickering backlight.

For a good discussion of Bob Pease's "April Fool" negative voltage generator, see:

Unfortunately you have to log in to the site to see the drawings & photos.

I don't think it produces nearly enough current to power an opamp.

Most of the audio section was done that way. But the product detector had low impedance output and the CMOS amp was too noisy at 50 ohms. A transformer might have done the job but a common-base amp seemed more practical and less prone to picking up hum.

Steve

I have a 1940s pistol drill that will generate a spike big enough to trigger the central heating on from the next room.

Martin wrote in news: snipped-for-privacy@news.gmx.at:

Ok, you found the skeleton in the closet. :-) You can not use this method to switch it off - but it is not required in most cases. Think of a cell phone - the backlight goes on every time you press a key, and it is going off after 10 seconds.

M.

"John - kd5yi" a écrit dans le message de news: snipped-for-privacy@enews2.newsguy.com...

And also take a bit less space on your bench :-)

Am Sun, 27 Nov 2005 09:57:23 +0000 (UTC) schrieb Matthias Weingart :

OK, so you can decide to not switch it on and save some mAs.

Early marine transmitters did it that way.

Known as "Klieg Eyes", (from "Klieg Lamp")

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)

Am Sat, 26 Nov 2005 22:35:18 -0500 schrieb Phil Hobbs :

OK :-) I liked to do that myself, but not from our 230V mains power, but with a transformer, 22V, and 30A short circuit.

Hello Jim,

Jim Thompson wrote: [...]

thank you, then I suppose the 2N3905 oder 2N2905 are fitting for a large signal amplifier.

mfg. Winfried

Jim Thompson skrev:

I've seen several speakers where there was a light bulb, in series with the tweeter, as a power limiter

-Lasse