IC solution is fine as long as it does not have any kind of oscillator (it is to be used very close to an RF circuit)Hi,
I assume you want no IC solution: Then use a motor-pot. Our TV set form the 1970ies worked this way.
Another TV set used several pots and a rotating switch to select the channel (pot).
The simplest IC solution: EEPOT (maybe with pushbutton interface).
Klaus
The resolution should be something like 256 steps in 0-5v, if not a completely analogue (step-free) circuit is to be used. I am not sure I understand what do you mean by the time span?Whats maximum time span for storing the V, and how accurate/resolution
do you need when you read it back ?
Regards, Dana.
IC solution is fine as long as it does not have any kind of oscillator (it is to be used very close to an RF circuit)
You mean these multi-turn potentiometers used on TV channels right? Hm...maybe the simplest idea is to have many pots and a way to switch between them, just like in the old TVs...
What is an EEPOT? these IC variable potentiometers? These do not have memories.
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The resolution should be something like 256 steps in 0-5v, if not a completely analogue (step-free) circuit is to be used. I am not sure I understand what do you mean by the time span?
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Maybe a 4017 (https://assets.nexperia.com/documents/data-sheet/74HC_HCT4017.pdf) can do it, by providing a voltage on each of its outputs to a trimmer potentiometer (one for each output).
This does not have any oscillator, so it should provide no RF interference.
But it's outputs operate on TTL levels and the maximum VCC is 6v.
Is there any other chip that can provide 8v or more to its outputs?
It sounds pro and way easier but too complicated for me unfortunately...Time span referring to how long between updates of voltage, worst case longest time
between updates/saves and read of voltage.
Thinking in terms of sample and hold circuit using a cap, again this depends on how often
you store the voltage to be saved.
Note this is a natural for something like ATTINY85, 8 pin micro, can be put to sleep
for low power operation, also reduce internal clock speed to reduce power and emi.
A/D is 10 bits, internal Vref. 4 channel mux if you wanted to do a cal routine or monitor
other stuff. Bypassing to suppress RF, because it draws very little current when operating
easy to do. Onchip EEPROM to store V value. Trigger to capture voltage, use PWM as D/A
to regenerate stored V, just shut it off after you do a read....., only external components RC
for PWM and a bypass cap......
View attachment 169072
Regards, Dana.
How long do you need to remember the voltage accurately?what do you mean by the time span?
Well it is a memory, indefinitely?How long do you need to remember the voltage accurately?
You can't store an analog voltage indefinitely.Well it is a memory, indefinitely?
I am trying to set the voltages on a varicap and an electronic attenuator (BJT-based). The 2 voltages will drive these elements so they behave in a certain manner on an RF circuit.Lets take another step back - what are you trying to achieve?
There may be a better way than the one you are trying to implement.
Susan
I can program (web). It is just that I have never spent time in MCU programming. I am going to look at mBlock or scratch for arduino, maybe it is an easy start for easy things that I want to do. I think that I will have to have the platforms to program these, but anyway.Sounds like you need to remember V's specific to each band ? The truly simple
effective way of doing this, accurately and repeatedly, is a MCU or a lot of programmable
logic and a memory element, dac, Vref.....a lot of parts.....
MCU.....hook up with a friend that can program, or start looking at videos on MCU
programming. If you know how to use a 4 function calculator you have been programming
for decades. mBlock is used now by youngsters to program robots. Many videos on this.
I advocate mBlock, or any of the other GUI programmers, like scratch for arduino, flowcode,
ardublock, visuino.... as a starting point. You learn one you can jump to others because they
are so similar. Note if you did Basic language in school there are some options to do this
with Arduinos.
Start simple, make a LED flash, change its flash rate, then make it turn on with a key press.
Build one step at a time.
Costs are cheap, a USB cable, and board, Nano or UNO more than enough.
Regards, Dana.
BTW, I have not found how on mBlock I can create arduino code it just creates python...I can program (web). It is just that I have never spent time in MCU programming. I am going to look at mBlock or scratch for arduino, maybe it is an easy start for easy things that I want to do. I think that I will have to have the platforms to program these, but anyway.
The other option is this one **broken link removed** if one wants to do it PC-free and without any MCU programmers in the loop. This can boot to a single basic program and LCD displays can be connected (there are libraries), so it can be used for the purpose.
I just thought it is a bit too overkill to use this powerful mcu for just reading/storing voltages and put them back, plus there is no DA converter there, plus the interference issue, which is really important in this particular application (which actually tries to eliminate QRM, not produce it)
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