Unusual functions of cheap parts

forward biased!

- Henry

"Oliver Betz" schrieb im Newsbeitrag news: snipped-for-privacy@z1.oliverbetz.de...

the

It also works for this: Vcc !/c --/\/\/\---+------! ! !\e V ! --- ----/\/\/--+--- too load ! ! --------------------

You get a current limit and an indicator light.

Can you give details?

- Henry

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

I posted some opamp schematics to abse a while back. I guess I could do it again if they're no longer available.

The others chould be fairly obvious.

John

A latch.

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.

It ran off 120 V. Parse the sentence as "two D-cell-carbon arc lamp." An earlier poster talked about building AC-powered arc lamps using the carbon rods from dry cells.

Cheers,

Phil Hobbs

Right, if CTR > 1.

John

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.

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.

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)

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

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

I put mine in series with Mom's iron, but the thermostat kept turning it off.