Electronics > Projects, Designs, and Technical Stuff
14.4V ground reference for ADC
Arjunan M R:
--- Quote from: Simon on May 20, 2019, 06:28:25 am ---
--- Quote from: Arjunan M R on May 20, 2019, 05:44:51 am ---The nice thing about the current sense amp(LT6105) is that its common mode input voltage can be higher
than its supply voltage. :-+
--- End quote ---
That is the whole point of using a current sensing amp like I was trying to explain. While they are opamps they are specifically designed to do this will do what a regular opamp will not.
--- End quote ---
:D :-+
Simon:
--- Quote from: Arjunan M R on May 20, 2019, 03:33:47 am ---
--- Quote from: Simon on May 19, 2019, 07:15:58 pm ---hahaha, i had not noticed. I say again to the OP, if your a programmer start on something simpler......
--- End quote ---
Yes i need to start on something simpler.But I decided to built this because i don't have a PSU and i needed one and i thought i can build one myself.Yes there are cheaper PSU s than my whole project costs and with more power(mine is only 18W) but they don't have that much precision.
--- End quote ---
You have the LT3080 regulator in your schematic. that is all you need for a basic PSU.
Arjunan M R:
--- Quote from: Simon on May 20, 2019, 06:33:49 am ---
--- Quote from: Arjunan M R on May 20, 2019, 03:33:47 am ---
--- Quote from: Simon on May 19, 2019, 07:15:58 pm ---hahaha, i had not noticed. I say again to the OP, if your a programmer start on something simpler......
--- End quote ---
Yes i need to start on something simpler.But I decided to built this because i don't have a PSU and i needed one and i thought i can build one myself.Yes there are cheaper PSU s than my whole project costs and with more power(mine is only 18W) but they don't have that much precision.
--- End quote ---
You have the LT3080 regulator in your schematic. that is all you need for a basic PSU.
--- End quote ---
I dont want just voltage regulation i also want constant current output to make sure my circuits don't blow up as i constantly makes mistakes :-DD |O
Simon:
Well.... you have the current sense amp and the LM358. i am not an opamp wiz but I think that if you connect the LM358 as a non inverting opamp with a little gain I think so that at full voltage drop on the sense resistor for 1A you have 18V out. Then connect a potentiometer to the inverting input of the LM358 so that you control the offset. Then connect the voltage setting resistor of the LT3080 to the output of the LM358 instead of ground. This way solong as the voltage from the current sense amplifier is less than the voltage on the inverting input to the LM358 the output of the LM328 will pull the voltage setting resistor to ground allowing full voltage. As the current rises and the voltage from the current sense amp increases above the set threshold on the -input of the LM358 the output of the LM358 will rise which will reduce the current in the voltage setting resistor of the LT3080 because there is less voltage difference across it and the voltage will "fold" to maintain the current.
Your valtage regulation will change by putting the LM358 into the voltage setting because it has some voltage dro so you need to experiment.
Arjunan M R:
--- Quote from: Simon on May 20, 2019, 06:59:31 am ---Well.... you have the current sense amp and the LM358. i am not an opamp wiz but I think that if you connect the LM358 as a non inverting opamp with a little gain I think so that at full voltage drop on the sense resistor for 1A you have 18V out. Then connect a potentiometer to the inverting input of the LM358 so that you control the offset. Then connect the voltage setting resistor of the LT3080 to the output of the LM358 instead of ground. This way solong as the voltage from the current sense amplifier is less than the voltage on the inverting input to the LM358 the output of the LM328 will pull the voltage setting resistor to ground allowing full voltage. As the current rises and the voltage from the current sense amp increases above the set threshold on the -input of the LM358 the output of the LM358 will rise which will reduce the current in the voltage setting resistor of the LT3080 because there is less voltage difference across it and the voltage will "fold" to maintain the current.
Your valtage regulation will change by putting the LM358 into the voltage setting because it has some voltage dro so you need to experiment.
--- End quote ---
No i am not doing it this way i am using a rotary encoder to set both voltage and current thats the main purpose of MCU . Using a pot. you cant accurately set the current. In my circuit i also have an lcd to display set and out I and V.And an opamp to set the current like shown in the schematic.The non inverting input of the opamp will be connected to output of the current sense amp and inverting input to the DAC(MCP4922 has 2 channels).So I can set the current using the DAC.
Note that i recently changed the MCU and didn't connect it
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