Electronic Circuits and Projects Forum

The updated circuit will control one pump, is that right?

I don't recall updating my circuit. Mine controls 4 pumps.

On the first circuit that controls four pumps, can each pump be independantly controlled?

No. You specified that the pumps would be operated in pairs. U3 and U4 independently control the 'on' and 'off' times of the first pair (pumps 1 and 2). U5 and U6 independently control the 'on' and 'off' times of the second pair (pumps 3 and 4). It would, however, be a simple matter to extend the circuit so that all four pumps had independent control.

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Edit: The following comments assume that your asking about the difference between the left and right side of colin55's schematic. And not actually talking about the difference between colin55's schematic and alec_t's schematic, which in fact uses a different but similar part. However, the point I make about needing to power the chip is still valid for both situations.
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"How come the IC is connected in a different way on each schematic?"

It's not really connected differently, that's just a power wire for the 74C14 chip. It's omitted in the right side of the picture because one 74C14 chip has 6 "gates" (the triangle shapes) for every two power wires, so the left side covers it. The 74C14 is not quite like a resistor or capacitor that can just be inserted into a circuit some where and work. It needs to have it's own power to do what it does. Most schematics are less than obvious about that because it's considered common knowledge, even if I would prefer they didn't do that.

What follows is a link showing you the guts of the 74C14 and some different ways to hook them up. In the first picture you can clearly see that pin 7 is a power wire and is connected to ground, just like in the left side of colin55's schematic. Also, the commentary for the third and fourth picture down briefly explains colin55's circuit. You can ignore the rest of the web page.

http://talkingelectronics.com/ChipDa...tml/74C14.html

Here's the extended circuit to give separate control of both the 'on' and 'off' periods of four pumps completely independently. Note that the pumps are each represented here as an inductor in series with a resistor. BTW, the 'asc' file that you had difficulty opening is for running a simulation of the previous circuit in LTSpice.

Yes, a simple zener reg could do it. I was feeling generous with the mA ;-)

I'll probably build your schematic that controls the pumps in pairs first

In that case, here's a revised form of the 2-pairs circuit which includes IC pin numbers and constructional notes. It incorporates Ronv's suggestion for a simplified 12V supply.