#1615

Episode 1615 chip of the day
true complementary devices
Be a Patron: / imsaiguy

[@ats89117]

Watching this brought back an old war story... Navy submarines used to have a roll of toilet paper mounted on each of the displays. It was fun to ask random people what the toilet paper was for. Very few realized it was to erase grease pencil marks...

[@dicko-200]

I still use my tp to remove "grease" marks. 😄

[@ke9tv]

Back in the day, it was pretty common to use one pair as a heater and temperature sensor, so that the second pair were held at a constant temperature. That way the kT/q dependency was taken out of the equation.

[@robertbox5399]

Isn't that similar to how a band-gap reference works? Use two transistors at different bias levels to remove temperature effects?

[@ke9tv]

@robertbox5399 this is more of a brute force approach: force the whole die to a known temperature above ambient by heating it. One of the four or five transistors in an array was just having current pushed through it to heat the chip.

[@Homer19521]

Always feel good about myself when I use complementary transistors 👍

[@joseppuig925]

I think manufacturers call then complementary when they share very similar limits in their specs such as voltage, current, power dissipation, frequency limit, and internal capacitances. Another thing is "matched" where they behave identical in their way of working, and that's what you see on the curce tracer.

[@tedivester4947]

Well it's back in the day - time again! We used to go through a bag of transistors testing for balance when using them in differential amplifiers. I really loved Tektronix curve tracers.

[@MsFireboy2]

Awe matched transistors in one package. This would be useful in the construction of differential amplifier circuits. Thanks for sharing.

[@andymouse]

Yeah, it's odd we don't see these around more.

[@MsFireboy2]

@@andymouse production cost mainly.

[@Hellhound604]

For matching small transistors, I use my analog discovery 2 with the transistor-attachment… you can store reference traces and compare them. But those old-school stuff just have so much charm to them.

[@edgeeffect]

Now I've gotta get myself a whiteboard marker.

[@ThermalWorld_]

Thanks.. I learned something new today 😄

[@d.jeffdionne]

I was surprised the Early voltage is so low on that 2N3906... so I looked at the data sheet and didn't see it specified. But Mot, er, OnSemi has SPICE models for each. And, behold! VAF is only 156 for 2N3906, and 1000 (that means 'large') for 3904. I'm a bit lazy to take the time to actually run curves in SPICE3, but it would be interesting to see how well they match the sample (of one) that you ran on the tracer.

[@IMSAIGuy]

old PNP designs all looked that way, that's what I remember

[@JRJJ5077]

That was interesting indeed.. 👍

[@andymouse]

I wonder why, as has been commented on that we don't see theses used in preamps and stuff where you might want a Current mirror and a differential amplifier all in one place and thermally coupled and matched and all that good stuff ? fascinating !...cheers. love chip of the day.

[@mnoxman]

Similar products are MMPQ6700

[@alklapaxida850]

i thought "complementary transistors" were when you walked in the store and they gave them to you free of charge . . .

[@robertbox5399]

We used a thing called BCV62 super matched pair. If it got heated by the PCB it would drift all over.

[@IMSAIGuy]

yes but did both sides drift the same?

[@robertbox5399]

@@IMSAIGuy One side was nearer to a coil driver FET which got warm. We fixed it by rotating the device 90 degrees.

[@IMSAIGuy]

@@robertbox5399 nice

[@AnalogDude_]

These are the harris, Intersil replacement parts from Renesas: HFA3046, HFA3096, HFA3127, HFA3128, Analog Devices also has a few. How would these perform?

[@aufoslab]

Experienced people like you, filled with knowledge, a treasurefor young generations to follow but no they are lost in distractions.

[@ivolol]

If you took ~8 2907s and ~8 2222s, did a quick'n'dirty measure of their betas, then took the best matched pair, I wonder how well matched they'd come out in the curve tracer?

[@ke9tv]

Usually Vbe matching has a greater effect in practice

[@jtabet010]

Love your videos, can you create one explaining how a curve tracer works

[@IMSAIGuy]

I did one: kzbin.info/www/bejne/eJLFdKikhZ6cmJosi=_k98qS240hi1Wbvq

[@bayareapianist]

Can you do a chip of the day for CD4007? Is there any analog use for it?

[@IMSAIGuy]

already did: kzbin.info/www/bejne/iJLXo6OghcuDrLMsi=nCp7dNJnZZR7rc-x

[@bayareapianist]

I have a good reason for those of you who wondered why these chips are obsolete. But I won't give it away until you guys tell me what you think. A few hints... 1) it is not the cost of the manufacturing. 2) something else replace these and people never look back at them. 3) say what replaced them?

[@mikebond6328]

mc

[@dicko-200]

do you ever use a wrist ground strap?

[@IMSAIGuy]

yes, but rarely

[@nickcaruso]

complementary just means n and p, matched characteristics is additional trait, right?

[@nickcaruso]

this is what people sometimes use curve tracer for- binning matched pairs

[@jeremycyclist6269]

Hi, I need 4+ pnp, paired transistors in single chip for mA range current mirrors. Do you know any?

[@IMSAIGuy]

CA3096 THAT320 I think it would be easier to search mouser for dual PNP

[@jeremycyclist6269]

Thank you @@IMSAIGuy

[@AnalogDude_]

7:30 is there another way to do this without that device?

[@stephentrier5569]

A multimeter's hFE function measures one point on those curves, so it can give you some data. If the bias the multimeter uses happens to match that of your target circuit that might be enough. Otherwise, you could breadboard something that provides the bias you care about and measure the gain around that bias point. This won't show the big picture like the curve tracer does, but it would let you match a complementary pair of transistors under the conditions that matter to the circuit you are building. With an oscilloscope, it's possible to build simple curve tracers. Look up "octopus curve tracer" online for a simple two-terminal version, or it's possible to breadboard a curve tracer that draws any one curve out of the family of curves IMSAI Guy's fancy curve tracer shows.

[@AnalogDude_]

@@stephentrier5569 Oh, thnx. But at the moment i do lack a good m.m., my "Home improvement" m.m. can measure 220V, but low voltages like 5V!

[@bayareapianist]

​​@@stephentrier5569too many word to say a simple thing. Like socpes, there is a fine tune knob on any good curve tracer to lower (but not increase) the current going to transistor's bais. They added this knob for exactly what he needed to do.

[@absurdengineering]

2N2907 should have higher beta than 2N2222. They are not matched at all per datasheet average specs. They look not much alike in SPICE too.

[@__--JY-Moe--__]

chip,chip. chip O de day! kenny rogers has nothing on this 1 !!

[@jagmarc]

What could the most unusual use for a quad transistor array: To fix temperature gage of a car was reading too low. Two PNPs wired as Current Mirror to amplify the signal. For every 1 mA of current going through the sensor to ground, another 1 mA of mirrored current sent directly to ground. Doubles the current coming from the gage and corrects the reading. Attached near temperture sensor.

[@IMSAIGuy]

I would make a hand warmer

[@Enigma758]

They are "complementary" not "complimentary" :)

[@IMSAIGuy]

can't you be both? 😀

[@ke9tv]

I'll compliment the way their characteristics so perfectly complement each other, if the spelling gets past the autocorrupt feature on my smart-a** phone.