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The whole point is to get the silver into the solution and to have as pure of a silver/water mix as possible.
Just as you would use an AC voltage for water detection, you use AC here. The crud builds up on one electrode and you have to remove it by reversing the polarity. This method is typical for electrochemistry.
I would guess the motor is a stirrer. If it is, I'd use a magnetic stirrer. Best would be a stirrer/hotplate. **broken link removed**
OK. I could not get the LM317 to act right for all the conditions, so here is the Fry's special.
Sorry, it is a bit more complicated but I think it will work for you.
Here are some things I noticed along the way.
The 10Ufd on the Con pin of the 555 should be a .01ufd.
You should have a 10 ufd. from 5 volts to ground at the 555.
I simulated with 4.7 Ufd. for the timing cap on the 555 and get 3 seconds or so with the pot at 50%. That would make your timing 300 seconds at 50%. I'm guessing this is what you want.
I didn't know what S2 Motor was so I tied the input of the NOR blocks to ground to make them active. Is S2 a timer or something?
I would make R8 220 ohms for the LED.
So here are the changes:
Replace the 317 with a current source.
Replace the base resistors with 150K,
Replace the transistors with Fry's available.
With this setup the single pot should get you from 1ma to about 12 or so.
I'm not sure I understand how this works since it would appear that it just plates from one electrode to the other and then back again. Does some of the silver stay in solution?
If so it won't take long for the resistance of the water to go down.
My bad, The other 2 BC547's can be replaced with 2N3904's which Fry's has.
Good luck.
OK. I could not get the LM317 to act right for all the conditions, so here is the Fry's special.
Sorry, it is a bit more complicated but I think it will work for you.
Here are some things I noticed along the way.
The 10Ufd on the Con pin of the 555 should be a .01ufd.
You should have a 10 ufd. from 5 volts to ground at the 555.
I simulated with 4.7 Ufd. for the timing cap on the 555 and get 3 seconds or so with the pot at 50%. That would make your timing 300 seconds at 50%. I'm guessing this is what you want.
I didn't know what S2 Motor was so I tied the input of the NOR blocks to ground to make them active. Is S2 a timer or something?
I would make R8 220 ohms for the LED.
So here are the changes:
Replace the 317 with a current source.
Replace the base resistors with 150K,
Replace the transistors with Fry's available.
With this setup the single pot should get you from 1ma to about 12 or so.
I'm not sure I understand how this works since it would appear that it just plates from one electrode to the other and then back again. Does some of the silver stay in solution?
If so it won't take long for the resistance of the water to go down.
Actually if your local Radio Shack has parts they should have the transistors, but they are quite expensive - then so is gas.
BH,
The 150 ohm resistors should be 150K.
LTSpice had trouble finding the operating point when I attached the IC's. Don't know what that was about either. I think it may work better with the 150K's.
Radio Shack is useless for parts. The biggest parts places are www.mouser.com, www.digikey.com, www.jameco.com and www.newark.com
Prefixes usually refer to the manufacturer. Thus an LM555, uA555,= and a NE555 are the same part. Then someone comes along like www.nteinc.com who makes replacement semiconductors with their own numbering system and calls it an NTE9555. CD4053 and an MC4053 are the same too and sometimes it's just referred to as a 4053 just like the 555 is. Suffixes could mean accuracy or temperature range etc. There may be date codes on an IC and country of origin codes.
Now there are "markings" and I havn't figured them out at all. There isn't enough room on a component to put all the numbers.
A 100 ohm resistor could be 100 ohm, 101. On a schematic it could be 100, 100R, 100., 100 Ω
Yea. it's a mess. I've been doing this since I was maybe 10 years old when there were tubes. Surface mount is driving me nuts.
then there are JEDEC registered parts: https://www.jedec.org/standards-documents/type-registration-data-sheets
When you see a k1024, you have to know to put a 2S in front of it to get 2SK1024.
You know kinda like s.i.g. T (2 dots over the T) PO B.I.D. for Write on label, Take 2 tablets by mouth twice a day.