how to have from 0.03 to 0.9 Volts DC output and 0.1 microamps (100nanoamps)?

[dedifferenciation]

Hello, I unfortunately know nothing about electronics but I need to build an apparel that can give me between 0.03 V and 0.9 V and also an amperage of 0.1 microamps (100 nanoamps), can someone please help?
Thank you so much!

 

[OlPhart]

A 1000 ohm potentiometer with 1 volt across it will draw 1 milliamp, should be well enough to source your 100 nA. If you can't allow over .9V or under .03V, fixed resistors of about a 91 ohm on the high side and about a 3 ohm for the low side.

 

[dedifferenciation]

thank you very much! I guess it means I have to build a circuit to put all that in. Is there a diagram I can follow somewhere? And also what do I have to choose to make the 1 volt?
Thank you!

 

[dedifferenciation]

the thing is, it absolutely cannot go above 0.1 microamp at all. It has to be the higher limit...

 

[carbonzit]

That depends: what's your source of electricity? hearing aid battery? diesel generator? wall wart transformer?

If you want to go somewhere, you need to know where you're coming from first ...

 

[dedifferenciation]

Ah OK, sorry. Well, I have no source of electricity yet. I only know that I need to have "0.1 microamp max per cm of electrode" ( just quoting) and "between 0.03 and 0.9 V max"... now I'm trying to figure out how to do that, never having touched electronic components in my life! Thank you!

 

[carbonzit]

You're dealing with extremely small amounts of electricity here. It also sounds as if you're going to be applying this to someone's (or something's) brain. Am I correct?

I'd suggest a battery power supply. Safe, and you'll be starting from a very low voltage (~1.5) to begin with.

What you need to work on is the current regulation. I was going to suggest a LM334 current regulator, but that will only get you down to a microampere; to get smaller currents than that, you're going to need some kind of current divider network.

 

[dedifferenciation]

, Yes! you are correct, teeth actually! I would like to see if enamel can regrow in a saline solution to which I would apply 0.1 amp and around o.5 volt and if there would be mitosis reversal, dedifferenciation and fast regrow from stem cells, but... I know so nothing about electronics I don;t even know where to start! I just know I absolutely cannot go over 0.9V.. and over 0.2 microamp...

 

[dedifferenciation]

is it complicated to setup a current divider network?

 

[dougy83]

is it complicated to setup a current divider network?

No it's not. If you have a 1.5V battery, connect the output leads of a 100k potentiometer across it; take one of the outer leads and the wiper lead and this gives you your variable voltage source from 0-1.5V. In series with the wiper lead, connect a large value resistor (or large value variable resistor if you can find one) - this allows you to set the current.

e.g. if you adjust the voltage with the first potentiometer to 0.5V, and connect a 10Megaohm resistor in series with the wiper, you'll get a maximum of 0.5V/10M = 50nA.

 

[dougy83]

The actual current will be diffused through the saline anyway, so is likely to be much less than this at any given point on the target.

 

[dedifferenciation]

ah...OK, I need around 150 nanoAmps, how can I have at the same time a max of 0.9V output (or rather 0.5) and 150nanoAmp please?

 

[dedifferenciation]

oh I see, but I will try it on dry enamel too...

 

[carbonzit]

I'd guess it would look something like this:

**broken link removed**

Rdiv would be a very small value. With the LM334 set for 1µA, 9/10 of the current would flow through it. The other tenth would go to your electrodes.

 

[dougy83]

ah...OK, I need around 150 nanoAmps, how can I have at the same time a max of 0.9V output (or rather 0.5) and 150nanoAmp please?

Adjust the pot to 0.9V out, use a 6megaohm resistor in series with this for 150nA max
For 0.5V, adjust the pot for 0.5V, use a 3.3megaohm resistor for 150nA max

 

[dedifferenciation]

Ah.. OK, thank you! just need to check what a LM334 is...

 

[dedifferenciation]

Ah. So it doesn't matter, I could do it both ways? OK. thank you.

 

[dedifferenciation]

Should I have a preference between the two, Dougy83 or CarbonZit? Or does it not matter at all? Is there something more I should consider?

 

[dedifferenciation]

Is there an approximate circuit drawing I can find somewhere to make the one you say Dougy83? ( I'm REALLY that bad...)

 

[carbonzit]

If you have a 1.5V battery, connect the output leads of a 100k potentiometer across it; take one of the outer leads and the wiper lead and this gives you your variable voltage source from 0-1.5V. In series with the wiper lead, connect a large value resistor (or large value variable resistor if you can find one) - this allows you to set the current.

e.g. if you adjust the voltage with the first potentiometer to 0.5V, and connect a 10Megaohm resistor in series with the wiper, you'll get a maximum of 0.5V/10M = 50nA.

But the problem with your scheme is that your high-value current-limiting resistor will also reduce the voltage being applied.