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thnx for great help Erik!
I think i will stick to the 8 diodes for now, dident understand your circuit so gna look closer at it later on.
I attached a simple circuit, with two signal inputs and 2 opamps.
I skipped the "safety" circuitry at the "end", just to keep it simple.
In this case the...
Hi again.
About to make a circuit board now, and a part of that is the oppamp circuitry we discussed above.
But i have to make 4 of them, becouse i got 4 different inputs.
Im looking to minizime the board, so im wondering if you could use the same "bias circuit" for all 4 Opamps, without...
Awsome stuff. Gna give that a go.
Cant rly say i understand the concept of a "protection voltage", but it will probably make more sense once i draw the circuit.
thnx for all of your help with this buddy.
tom
Got the opamps last week, made a small circuit bord so i can connect myselfs to the pins.
The circuit is working good, and almost rdy for the ADC input.
About the ADC protection, i figured i will supply the oppamp with 3.3 volts or smth to deny any higher output.
And about blocking the...
yeah lol, i ment A = 2, not 1, sry.
Thnx for all your help buddy, the oppamps should arrive some time this week, so abit on hold at the moment, ill keep posting once they arrive.
Regards: Tom
Ok, here is the same simulations with the tlv2262, looks abit better
And i should add to the simulations before, the opamp settles at more expected values after a short time. Say i put start time 50ms and end time 60ms, instead of 0 and 10ms. The output is completely different.
So that kinda...
Been doing some simulations with the LM324 now, with a +-250mV input signal.
Seems to me that this opamp cant handle the 10Meg resistor at the input, not sure.
the input bias current is typ 45nA. 45nA * 10Meg = 0.45 V of extra input.
Maby thats the point, not very steady on this stuff, just...
Awsome stuff guys! Thnx alot!
Did not have time today to check it all out, but gna try to take some time tommorow.
And yeah, deffinatly going for a fet input oppamp.
Anyways, ill post my progress when i have more time.
thnx again, have a great weekend
Regards: Tom
Think i can use this circuit (follower), if i can find a suitable opamp.
Singly suply. and very high input impendance.
The 324 opamp works well when i use resistors 20k and 220k, but i need to able to use way larger resistors. 2M and 22M or even higher.
Its abit hard to find a suitable one...
Heres pics of voltage at opamp output, and inverting input.
Maby i missunderstood then concept of biasing, and that i need to add some more to my circuit?
Hey, again thnx for your help!
checked out the datasheet for LM324 / LM2902, but i think theres an issue with the input voltage range. its says that -0.3 volts on the input is as low as it goes before the output goes to V+.
Does that go for an AC signal?, or is it -0.3 dc ?
And my input...
Ok bro, ill try that. thnx heaps!
Never used a voltage divider at the opamp output before, but then again, im no expert :)
Added after 1 hours 46 minutes:
Something likes this you had in mind?
when i simulate this, the center point is around 2.8 volts. which is a bit high, and i cant seem...
Hey guys!
Would be awsome if anyone pls could take a quick look at my problem.
Got a +- 300 mV input singal comming from a piezo electric sensor.
My ADC works in the range 0-2.8 V.
So iam gna bias the input signal with 1 volt. I need to take advantage of the opamps high input impedance, so...
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