No problem. It was the collector! My guess at a reason is that there's more area. (aren't the emitters smaller than the collector.. basically the substrate ???)
It'd take too long for JL's 60k ohm to get here :^), so I stuck my favorite 10k ohm across it.
I LED I sc V/10k ohm (mA) (uA) (V) ________________________
10 47 0.45 20 96 0.525 30 143 0.55 40 188 0.56George H.
I recall a TI IR photodiode (TL1xx ??) which produced around 1mA in ordinary room light, and more then 20mA outdoors in the Arizona sun. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Well! That's not very thrilling :-(
I remember playing with plates from a Selenium rectifier when I was a kid. Wonder what that puts out? ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
You told me to check the supply current. I saw 9 mA peaks with a 1.5 us edge, which you called "horrendous", which statement makes no sense. I'm thinking that, in your eagerness to be critical, you looked at the shape but not the scaling.
So: is 9 ma with a 1.5 us risetime a "horrendous" current spike?
I don't do IC design. It doesn't interest me. You seem to be pretty good at it, as long as you don't get off-chip. But, as I've said, you couldn't design any of the stuff we make.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Right. Shorting b-c makes it a better diode but a much worse solar cell.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
I said short c-e. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
I just tried a 3mm red led held under a desk lamp, 1.35V
-Lasse
I think we've got some opto-coupleres with better than 50% CTR... I'll have to look see. (dang it's a photo transistor (MCT62) I thought the detector was just a diode...)
OK not to be out done I got a big ass photodiode (PIN 10DI) (100mm^2 area.. we pay ~$35 a piece for these babies.)
And I've got a little IR LED that I know puts out a lot of photons op233
with 10mA of LED current (1.24 Vf) I could only get 700 uA SC from the photodiode. ... 7% CTR, you still beat me... maybe I win at energy transfer... but it's still pretty poor.
George H.
Sounds unlikely. My Vishay part is huge, 7 sq mm active area, and it makes a few uA in room light, 100 lux, and around 2 mA in sunlight, over 100 Klux.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Probably. The Cree makes a lot of blue, and the pd is almost blind up (down?) there.
I tried a couple of handy IR and visible LEDs, but the Cree still wins. It's shockingly bright at 20 mA.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Not unlikely. It's in a plastic transistor package larger then a
2N3904, whatever package style that is, so the die can be huge. (7mm^2 isn't huge... I have custom chips 10mm on a side, 100mm^2.)(Original usage was for IR TV controls, back around 1985.)
I was last using them to look skyward and find the prop modulation from CHiP's aircraft flying speed traps out of Blythe ;-) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
still sound like much
-Lasse
I think the issue is, that the full power-supply noise (of the op amp power supply) gets through. I'm thinking that the triangle-wave (if derived from a saturated square wave) has a nice RC filter, and is regulated by the triangle-wave range switching (accurate P-P voltage, even if there's some RMS uncertainty).
A '555 with the CTRL pin set to a well-regulated voltage, generates a constant-amplitude triangle wave (instead of constant-frequency). Yeah, OK, it's not exactly a triangle, but good enough for power-supply uses, and amplitude is independent of power supply noise.
I'n not so much concerned with the power supply noise getting into my step-up converter. The real concern is noise generated by the converter getting into a photodiode front-end.
If I drive a transformer and rectify the secondary, there will be current peaks at the top of the triangle, charging the caps. Load regulation will be poor.
One problem with a triangle is that it *doesn't* rail the opamp, so you have to give up some signal swing to keep the amps linear. Maybe you could use a triangle that does clip, saturate the amps at peak swing, but then it's a trapezoid, morally equivalent to my square wave with low slew rate.
My goal is to keep di/dt low everywhere in the circuit. The opamp that I want to use will slew in a few microseconds, which is super soft compared to some CMOS 555-type thing, or some switcher chip.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
What's unlikely is the 20:1 current ratio, when the light ratio is probably over 1000:1.
We'd have to see that TL1xx date sheet to learn more.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
It's much like an MOS device, limited carriers. Ask Phil.
I'm trying to remember the part number. I'm sure I have some around here somewhere. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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But fast compared with the sine waves you've got in a Baxandall class-D osc illator. You do a have a lower frequency limit with the Baxandall approach, set by the onset of magnetic saturation in the transformer core, but max d i/dt is going to be lower than anything you can do with a triangle wave gen erator.
shows very soggy switching. Since the DMOS switches won't squeg, you use a much bigger inductance at L3 than I did.
-- Bill Sloman, Sydney
No, I was thinking if you clipped off the top of a triangle, just right, you could tune down some harmonic*.. it's much more like a sine, and you could drive it right up near the rails.
George H.
*this must have been mentioned here before... I recall some theory number.. how much to cut off.
Or use a real sine wave, a single-transistor Colpitts oscillator maybe. Nice and soft on top.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
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