Neutron Filter questions

[mat]

Hello,

Does the Neutron Filter ( http://www.geofex.com/PCB_layouts/Layouts/neutronpub.pdf ) need a bipolar -9/+9 power ? Or can I build it with two 9v batteries in series without the charge pump. If so, where to put the - and + wires ?

I was a little confused with this one so would be nice to know how should I proceed.

Here is the circuit so far:

http://tinypic.com/551pjp

The ldr/led section is not yet covered or soldered.

On the parts layout there is on the upperside a resistor in series with the C14 cap. It reads R18. I think it should be R21.

Another question. Can I still use the power on in the input jack trick (with the Q1 and R20) while I did not put in the power section (U4, C15, C16, C17).

Can't wait to get this ready  

Thanks R.G. for a great project !

mat

[R.G.]

You can do either a bipolar power supply or two batteries. It may eat batteries quickly, but they'll certainly work. Hook them in series, then tie the free + wire to the + power input over on the wire-leads side of the board, the - to the - power input same place, and the joined + and - in the middle to the ground connection. + , ground, and - are three pads in series in the row of wire pads.

You'll have to put a power switch in there to switch the batteries off. Switch both the + and - power wires, not just one. Using two batteries, you have to switch both wires, and the input jack trick only switches one. If you do both the input and output jacks, that works, but then the power is only really of if you pull out both input and output jacks. It is possible to make a combined + side/ - side power switch that works from the input jack. See the hum free signal splitter at GEO, http://geofex.com/FX_images/splitter.gif. The power switching is just the part inside the dotted line.

Yeah, that R18 is a typo. Should be 560 ohms. The real R18 is on the board, connects to C10 and R19.

[mat]

Thanks for the really quick answer  :shock:

Your explanations cleared the foggy parts to me complitely.

I started the hobby at last june and I've visited Your site for time to time. While slowly learning more and more day by day I'm starting to realize Your Website being some kind of never ending treasure locker  :shock:        

BIG Thanks for You effort !

mat