2N2222 Zener noise

voltage?

is in series with > the zener stabilizes the effects between the two.

Another miss informed idiot..

I understand why they blow up at you.. You're just a waste of BW.

Oh, ok we're on the same wavelength after all.

Where are the knobs and display? Is there a good ready-made PC GUI program to control it? Or is it a very straightforward terminal command set that I can learn in a few minutes?

Sample memory isn't very deep. But arb. isn't my usual application. 4 channels is a plus, since I may want to tinker with 3 and 4-phase stuff.

What's the sample rate for the freq. ranges?

What are the sine wave distortion specs in the audio range?

I like the fine phase setting. I have a need for about 0.01 degree resolution for a PLL system at work. But I think my system already has it built in. I have to check what phase resolution is possible with the uC based frequency source in that.

What about external inputs for AM, FM, PM, PWM, summing, etc.?

Can I externally trigger pulses? Can I set a pre-delay? What resolution? Burst mode with 1, N, or infinite pulses? What is minimum pulse width? Are edge rates configurable?

Please send me a quote and a manual if possible. Please decode email address below.

--
_____________________
Mr.CRC
crobcBOGUS@REMOVETHISsbcglobal.net
SuSE 10.3 Linux 2.6.22.17

As far as i know, the lowest breakdown of any silicon E-B junction is

6V and typically you will see 8V or more despite literature "specs" saying they ALL are 5V. You definitely will never see 3V breakdown of standard "sand power" transistors. Maybe if you get into the exotic microwave, HEMT, etc stuff...

voltage?

is in series with > the zener stabilizes the effects between the two.

Yeah, the whole world is wrong, except DimBulb and Jamie. We got it.

Information is not a waste of bandwidth. You, OTOH,...

Certainly not white noise. Nearly all opamps have a 1/f noise corner.

John

voltage?

The serial comm protocol is very simple. We do have a PC gui thing, but it doesn't support all the features.

The DDSs always run at 128 MHz. It also does sample interpolation, from the waveform mamory up to the 128 MHz DACs, which somewhat mitigates the small memories. All the wavegen stuff is onboard a Xilinx FPGA, which limits memory size.

Around -60. What was really hard was to keep the distortion down below

-50 or so all the way to 32 MHz. It's not unusual to see RF signal generators with -20 dB distortion specs.

We didn't do that. Maybe next spin.

Yes, mostly. I'll email you the manual. One thing you can do is use the memory of one channel to build a microengine the sequences other channels, to do really complex stuff.

OK.

John

Some silicon microwave transistors have very low rated max reverse Vbe, which may be an artifact of their very abrupt junctions. I'll measure some next week, maybe.

I've seen PNP silicon transistors that zenered at around 12 volts.

John

Not that unusual. Regular silicon in the 1GHz range will zap under 5V. Find them all the time in video amps and such.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

It is cheap! Also, it supposedly works down to 2.3 volts, so it should be possible to use it with a 3V lithium ion coin cell as the supply.

I think I'm going to use that approach. I experimented with some blocking oscillator circuits in LTSpice today and I think I've found a setup that will generate a high enough voltage to produce avalanche noise from a reverse biased emitter-base junction. I had to experiment with putting some series resistance before the circuit to prevent it boosting to a ridiculously high voltage with a light load, and drawing so much current that it drags down the supply across the coin cells relatively high ESR. For better efficiency I may put in a simple base-current robbing control loop as you suggest.

is

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I once measured some BF199 transistors and it felt like they had BE breakdown voltage about 1V or so.

That's because the spec's for that component specify close to 925mv for Vbe

Looks like a general purpose component..

Jamie.

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diode is in series with > the zener stabilizes the effects between the two= .

Jamie has achieved something remarkable. He's got krw agreeing with me, and me agreeing with krw.

This implies that Jamie has has posted something that really is remarkably stupid. If there was any room for a difference of opinion, it can be taken as read that krw and I would disagree, but Jamie has managed to reach hitherto unplumbed depths of stupidity.

-- Bill Sloman, Nijmegen

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voltage?

For bipolar op amps the noise corner is close to 10Hz. You don't have to leave your frequency window open much above 10Hz for the white noise to swamp the 1/f noise, and you can always high-pass filter the noise to get rid of the 1/f contribution.

-- Bill Sloman, Nijmegen

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BFR92 has a base-emitter reverse breakdown voltage of 2V. It is a broadband part, but Farnell stocks it and has 7153 in stock at a price equivalent to $0.61 each, which is pretty close to a "sand power" transistor. IIRR most cheap broad-band transistors have similarly low base-emitter breakdown voltages. It's PNP complement - the BFT92 - has the same 2V specification.

-- Bill Sloman, Nijmegen

The BFP620 has a 1.2V abs max rating for Vbe and Digikey has them in stock for around a buck in small qties.

At 65GHz ft this one can be considered a hotrod.

--
Regards, Joerg

http://www.analogconsultants.com/

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Use another domain or send PM.

voltage?

Most are higher than that, if it's specified at all. And opamps can have very non-Gaussian behavior, like temperature driven offsets, popcorn noise, ambient RF rectification, PSRR issues. An opamp isn't a very good noise source. A zener can make several hundred nV/rthz of pretty high quality noise. A PN shift register is almost perfect.

John

Is that the abs max datasheet spec, or an actual, typical zener voltage?

Lots of RF parts have very conservative reverse voltage ratings. We use schottky diodes at -6 volts, that are rated for -2.

John

On a sunny day (Sat, 27 Nov 2010 11:17:43 -0800) it happened John Larkin wrote in :

Long time ago there was a discussion here about degradation of RF transistors when used as zeners, from that arises the question how long such a RF transistor would last as a zener,

It probably lasts a long time. However, a transistor that had been used as a zener with their BE path should not be put back into the parts bin. There can be deterioration in it's normal job function, as a transistor.

--
Regards, Joerg

http://www.analogconsultants.com/

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