Single capacitor integrator switch placement

[pustareka]

https://www.edn.com/instrumentation-amp-makes-noninverting-integrator/

[pustareka]

no.

[6666]

BAD BAD

хорошо - super

Does the ring guard on pin 2 make any difference ?

[pustareka]

[pustareka]

BAD BAD

хорошо - super

[Carl-NC]

Are you selecting the inverter input and fdbk resistor and the two integrator input resistors? What tolerance? Maybe 1% resistors is close enough? 1% of 10k is 100R, lot more than switch matching.

Yes, I use 1% resistors everywhere. Almost all my designs are SMT.

[green]

That's what happened in the TDI-SL... the input R is 10k so I eliminated the trim pots. Other designs I've done go down to 1k but I tend to use better switches than the 4066, so I still never use a trim pot.

Are you selecting the inverter input and fdbk resistor and the two integrator input resistors? What tolerance? Maybe 1% resistors is close enough? 1% of 10k is 100R, lot more than switch matching.

[Carl-NC]

Yes, it is matching between channels that is important rather than absolute value and interesting that the MAX4066A is 2Ω max. per channel. Some of the integrators I use in detectors with high pulse rates have 10K input resistors, so 2Ω or less is insignificant.

That's what happened in the TDI-SL... the input R is 10k so I eliminated the trim pots. Other designs I've done go down to 1k but I tend to use better switches than the 4066, so I still never use a trim pot.

[Ferric Toes]

Never used jfets personally. For 4066 chips I think it depends on the model. For example TI's CD4066B datasheet says "Switch On-State Resistance Matched to Within 5Ω Over 15-V Signal-Input Range", which I understand is matching between channels. That's not 1% compared to the switch on-resistance itself but with 1k resistor in series its pretty decent. Some other datasheets don't mention matching at all. Also I wouldn't put that much faith into the unmarked 4066 chips I got from China.

I use MAX4066A because it can be driven directly from a 5 V micro. This one has 2Ω max and 0.5Ω typical match between channels.

Yes, it is matching between channels that is important rather than absolute value and interesting that the MAX4066A is 2Ω max. per channel. Some of the integrators I use in detectors with high pulse rates have 10K input resistors, so 2Ω or less is insignificant.

Eric.

[Cazavor]

I wish! I make plenty of blunders and often post them right here!

Well not as much as us new players

I always use 1% resistors too, but as the Rds(on) of the jfets, or the gates in a 4066, are not balanced to 1%, I use a trimpot to compensate for this.

Eric.

Never used jfets personally. For 4066 chips I think it depends on the model. For example TI's CD4066B datasheet says "Switch On-State Resistance Matched to Within 5Ω Over 15-V Signal-Input Range", which I understand is matching between channels. That's not 1% compared to the switch on-resistance itself but with 1k resistor in series its pretty decent. Some other datasheets don't mention matching at all. Also I wouldn't put that much faith into the unmarked 4066 chips I got from China.

I use MAX4066A because it can be driven directly from a 5 V micro. This one has 2Ω max and 0.5Ω typical match between channels.

Which version of the
1C integrator did you make ?

The classic one with resistors before switches. Schematic attached.

[Qiaozhi]

I wish! I make plenty of blunders and often post them right here!

"A person who never made a mistake never tried anything new." - Albert Einstein

[Ferric Toes]

The EF trim pot I use is 1% of the input resistor value. Easy to see adjustment when moving a ceramic magnet away from coil. Don't remember if EF was a problem if pot was adjusted to either end(1% difference in input resistors).

I always use 1% resistors too, but as the Rds(on) of the jfets, or the gates in a 4066, are not balanced to 1%, I use a trimpot to compensate for this.

Eric.

[Carl-NC]

You're right as always Carl.

I wish! I make plenty of blunders and often post them right here!

[green]

The EF trim pot I use is 1% of the input resistor value. Easy to see adjustment when moving a ceramic magnet away from coil. Don't remember if EF was a problem if pot was adjusted to either end(1% difference in input resistors).

[6666]

You're right as always Carl. When using precision components, such as 1% resistors or better, a potentiometer is not needed at all.

My problem turned out to be a very simple mechanical one. Namely the BNC plug and socket I bought from my local electronics shop made only an intermittent connection at best. I did not suspect that all since those parts were brand new.

Some people on the internet are saying that 50 and 75 ohm coax connectors have different parameters while others swear that coax connectors are all the same. I don't know what to think about that.

For now, I just did away with all the connector stuff and made a direct coax connection from the coil to the control box. Works perfectly.

Which version of the
1C integrator did you make ?