So as the title says i need a little bit of help to create this filter, i was able to calculate everything for my desired cutoff (80hz) and was able to build everything it works but there is a+
strange behaviour:
this is the circuit i followed (did twice having 2 op-amps in a single one) i am using a KIA 4558P but following the circuit for the gain feedback circuit (r1-r2) it doesnt filter anymore it doesnt even work if i dont want to use the gain and just wire directly the output to the inverting input it still doesnt work, but the moment i connect the output to the non-inverting input (+) it does work but now i dont have gain and loose usable power of the sub.
sorry for bad english not my main language, sorry for wrong words/terms eletrical engeenering is not my main subject is just a hobby. Thanks in advance
strange behaviour:
this is the circuit i followed (did twice having 2 op-amps in a single one) i am using a KIA 4558P but following the circuit for the gain feedback circuit (r1-r2) it doesnt filter anymore it doesnt even work if i dont want to use the gain and just wire directly the output to the inverting input it still doesnt work, but the moment i connect the output to the non-inverting input (+) it does work but now i dont have gain and loose usable power of the sub.
sorry for bad english not my main language, sorry for wrong words/terms eletrical engeenering is not my main subject is just a hobby. Thanks in advance
The circuit is basic, and it should work OK as you draw it, just two comments:
1-It requires dual power supply (+/- Voltage) if not it will not work (-In is referenced to ground).
2-The input is DC coupled (+In), so you need to be careful with the previous stage, or you may add an input cap to block DC if you application allows to do it.
Good luck
1-It requires dual power supply (+/- Voltage) if not it will not work (-In is referenced to ground).
2-The input is DC coupled (+In), so you need to be careful with the previous stage, or you may add an input cap to block DC if you application allows to do it.
Good luck
Yes, check the power supplies.
But first add a 20k resistor between the signal input Vin and ground, so the positive input has a DC path to ground.
What values are you using for the R and C parts?
But first add a 20k resistor between the signal input Vin and ground, so the positive input has a DC path to ground.
What values are you using for the R and C parts?
i dont fully understand the point 2, could you please explain a little bit easier, this op-amp strangely doesnt require a dual power supply but it will work relatively bad, i use a dual power supply but still the same problem
rayma sorry i cant reply to you my R and C values are 10kohm and 200nF, why should i but the resistor beetween the signal input and ground?
The positive input needs a DC path to ground (through only resistors) to function. That might be the problem.
Probably it's best if you post a complete schematic, including power supply.
Something probably isn't hooked up right.
Probably it's best if you post a complete schematic, including power supply.
Something probably isn't hooked up right.
this is the literal connections i do on my breadboard but i dont have a star-kind gnd point but i have 3 gnd points. I hope its clear enough
Your circuit as it is drawn has a DC gain of (1+R2/R1), so if the source has a DC offset voltage it will be amplified, and it may overload/saturate the circuit
Ok, your problem is that this is a single supply circuit, and you need to add the proper biasing for the inputs,
along with input and output DC blocking capacitors.
This will complicate the circuit, so it's preferable to use a bipolar supply, +12V and -12V and ground.
If you have to use a single supply circuit, let me know.
along with input and output DC blocking capacitors.
This will complicate the circuit, so it's preferable to use a bipolar supply, +12V and -12V and ground.
If you have to use a single supply circuit, let me know.
maybe the drawing isnt well made, i am using a dual power supply, and it works but i left the middle point the gnd without anything because it simply doesnt work if i connect the gnd to the powersupply gnd, but it works if i connect the gnd to the minus of the input/output
By dual power supply, do you mean that there are two independent supplies, each with two terminals?
Or just one supply with a total of two terminals?
Here is the data sheet pinout. This is a dual op amp.
+in pin 3
-in pin 2
out pin 1
+in pin 5
-in pin 6
out pin 7
+ supply pin 8
- supply pin 4
Or just one supply with a total of two terminals?
Here is the data sheet pinout. This is a dual op amp.
+in pin 3
-in pin 2
out pin 1
+in pin 5
-in pin 6
out pin 7
+ supply pin 8
- supply pin 4
yes i checked them many times, and checked them with the same document rayma gave me. i tried making a simplier version of the circui (1st order) so i get less incasinated and surely get the right connections but still nothing
Maybe the solderless breadboard is the problem. There can be open circuits where you don't expect them,
especially in the rails at the sides of the breadboard. Or there can be defective contacts.
especially in the rails at the sides of the breadboard. Or there can be defective contacts.
by dual power supply i mean i have a +12V and -12V and a "middle point" of 0V
about the pinout i checked it several times and made more than once with different breadboards too
i dont know about the solderless board, pretty strange because by this logic the whole filter shouldnt work but in my case only the gain sector of my filter doesnt work
The schematic shows, among other things, that the output is on pin 5 and the supply on pin 3, which is incorrect.
i think that the schematic created is wrong, im not an expert the supply of -12V is on pin 4 and the supply of +12V is on pin 8, the output is on pin1 that goes back to pin 5 and my final output is pin 7 for a 2nd order or for a 1st order finishes on pin1
I would suggest drawing another schematic with all the pins labeled correctly.
Then compare it with your breadboard.
Then compare it with your breadboard.
arleady did that unfortunatly it still doesnt work, i hand draw that so its easier for me to understand during the check
Ok, then if you have a good schematic, I would remove all parts from the breadboard and start over.
There's also a chance that the op amp is damaged.
There's also a chance that the op amp is damaged.