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@betwixt, Thanks for your suggestions. I did read the datasheet and it is not mentioned that a minimum output current is required. What is this parameter usually refered to please? Also, are the 100nF caps necessary?
@KlausST, I need the circuit to operate at either 3.3V or 5V (sorry, in my...
Thanks for the replies.
@KlausST, Coincidentally I was considering the LDO option.
Following some search, I am now considering the LD2981 (3.3V and 5V versions). These are ultra-low dropout regulators, so they should work fine for my appliction.
A quick question, since Iwill be using two...
@KlausST, Let me explain my circuit better as it looks like my previous explantation was not so clean.
I have a simple signal conditioning circuit (filtering, rectifying and enveloping) which can operate at 3.3V to 5V.
As for the power of this circuit, I intend to have three options (switch...
Hi KlausST.
Thanks for your reply. As already stated, no I did not simulate the circuit as most of the parts being used (including the zener diode) are not included in the simulation library. The name of the zener was edited by myself and not selected from the part list.
No I am not expecting...
Thanks for your reply @betwixt.
My main concerns are the following:
1) Is the max current of the zener 200mA? It is not listed in the datasheet, but the description on Mouser states that Zener Current is 200mA.
2) You mentioned that I have to use R = V/I where R is 'R0' in your schematic, V is...
PS: I did not simulate the circuit as this zener diode is not available in the library, but I did a simulation using the 1N5231B and the results were kind of promising (3.3Vout when input was 3.3V, 4.95Vout when input was 5V and 5.21Vout when input was 12V)
Hi all,
I have a circuit which consists of some quad op-amps and other low power ICs.
As for the input supply, I am going to use the supply from microprocessor development boards (either 3.3V or 5V).
As an extra protection for the circuit, I was planning to include a 5.1V zener diode so it...
@Audioguru, The input is sourced from an instrumentational amplifier which has low output impedance.
@zorro, yes the actual circuit has R2 connected to 1.65V. The one attached is the first version on the circuit. Thanks.
Hi again,
I designed the high pass filter with a cutoff of 20Hz and used another op-amp for the variable gain, as suggested.
Is the design good for attenuating frequencies below 20Hz? Are the values selected correct or should I select smaller value capacitors?
Also, when I checked the frequency...
Thanks for the replies. So the only way to apply variable gain is to use another op-amp at the output? and for these requirements (i.e. a filter which can attenuate frequencies from 0Hz to 20Hz), which filter design would you recommand? is it the Sallen-Key, the multiple feedback or any other...
Hi again. The low-pass filter is already implemented. The problem is with the high-pass filter. I want the high-pass filter to have adjustable gain with a potentiometer and a fixed output offset of 1.5V. The filter needs to be powered from a single supply rail.
I was testing the Sallen-key...
Thanks for the reply. Is there any similar circuits with a gain not dependent on the frequency?
I tried a 2nd order Sallen Key filter. The problem with the Sallen Key is that I need an offset of 1.5V at the output of the filter. To obtain this I need to apply -1.5V at the negative input of the...
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