Battery Only Wiring

[joeychickenskin]

Hi

I've built an SHO which sounds great if it wasn't for the horrible hiss which after building a second one, I realise is my power source (test everything means test EVERYTHING).

I'd like it to be battery only as if I put a dc socket in I'm likely to forget not to use it.

I have apreviously built battery only pedal that has a true bypass 3pdt switch and seems to still drain the battery when switched to bypass/connected to the guitar cables.

Short of including an on-off switch to the middle of the battery snap positive cable, is there anything simpler that I can do.

Sorry if this is posted elsewhere I've searched the forum and through google for 'battery only stombox wiring'

Thank you

[Mark Hammer]

The simplest thing is either to use a pot with an on-off switch, or else install an on-off toggle, so that you can leave the unit plugged in and set to whatever gain setting you want, and still be able to turn the battery off.

[duck_arse]

stick some batteries in a box with a big on/off switch and all the leds you like, with standard leads/plugs attached. fit standard external supply socket to your battery-only box, plug battery box in, away you go.

as I was typing this, I spotted a few possible hitches in use, but it'll surely work.

[PRR]

> horrible hiss which..., I realise is my power source

So filter the power source inside the SHO.

[joeychickenskin]

Thank you

I've added a couple of large filtering caps (with the circuit attached to a breadboard) which cut the hiss at a couple of frequencies but still left an unacceptable amount of hiss (I'm by no means precious but the SHO gives the guitar sound a shower and a shave but the hiss is still too much in return).

I'm going to build a humminator but I suspect I will need a better supply in due course but am eager to finish this project so will go with a battery.

I would use an on-off pot but if it replaced the pot on the SHO, cutting to off wouldn't prevent the battery drain as I assume this is due to the 9v+ve lead being attached to the circuit board which is commonly grounded - I'm fairly new to electronics so I may have this wrong).

I think I'll use an on-off toggle switch, I just wanted to check that there wasn't someting simpler that I was missing.

If I use a dpdt can I also take a second LED from the +ve battery wire to the lug adjacent to the wire-to-board wire so that it reminds me to turn it on?

[Jdansti]

Maybe I missed something, but if you want battery only, why not run the negative battery lead to the ring of a stereo jack so that it turns on when you plug in your guitar cable and turns off when you unplug it?

[davent]

In addition to the caps for filtering did you add some series resistance before the cap, 100r or so?

[R.G.]

In addition to the caps for filtering did you add some series resistance before the cap, 100r or so?

+1 - and by extension, a ferrite bead?

The SHO is a special case of difficult for EMI problems because of the very - very! - high input impedance and otherwise little notice of RF issues.

I would filter the power supply, AND put a 0.1uF dipped ceramic cap across the power on t he PCB, AND put a series resistor of about 100R right at the gate lead of the MOSFET.

AND hope... 

[joeychickenskin]

Thanks everyone, very helpful.

Of course! The negative power lead to the ring terminal like you do with dual adaptor/batteries!

I think what's thrown me there is that I have a pedal that I wired for dual power and the pedal didn't power with a battery with the negative terminal of the power jack wired to the ring. I found a separate wiring diagram (Beavis Audio I think) that had the wiring going jack negative terminal to ring to sleeve which made sense as it completes the common ground (does this mean that my circuit is drinking battery power as I type) . I wonder why why wiring the ring didn't work, I'll look at it again.

I'd like to lick filtering in the pedal because the same power source is fine with some pedals that I've built (including, curiously a Hyperion with no power filtering is fine) and commercial pedals are fine so it would be good practice to make the pedal more resiliant to noise. I hadn't included resistance before the caps.

Can anyone suggest (or point me to) the components I need to put accross the 9v and ground rails of my circuit to illiminate power supply noise. Is the humminator fairly robust?

I hadn't come accross ferrite beads before. My usual components shop (bitsbox) doesn't seem to have them. Are these the ones http://www.ebay.co.uk/itm/100-Pcs-Axial-Lead-Cylinder-Body-Ferrite-Beads-Leads-Black-/190897272322?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item2c725d3602?

Thanks

[davent]

This was my source of info when i was having the same issues with an AMZ Mosfet Booster.
http://www.muzique.com/lab/hum.htm

[duck_arse]

joey, go here:

http://www.muzique.com/lab/main.htm

read everything that looks interesting, especially "Hum & Noise in Effects" down near the page bottom.

those are ferrite beads, but the ones you probably want have a hole up 'em, so you can slip them over the leg of a troublesome transistor.

http://www.ebay.com/itm/Ferrite-Bead-type-FB43-101-Lot-of-20-pcs-NEW-/151245360376?pt=LH_DefaultDomain_0&hash=item2336ed0cf8
http://www.ebay.com/itm/100pcs-Ferrite-bead-can-fit-TO-220-TO-3P-transistor-pin-/131091028786?pt=LH_DefaultDomain_0&hash=item1e85a25b32

for example and etcetera. I dunno if the are "the" ones, but they are ones.

[edit :] the slowness of my typing is matched only by the slowness of my innerwebs connection. what ^ he said.

[davent]

Duck if i had typed as much as you did in your post (and links), you would have beat me. There's slow and then there's me.

[duck_arse]

ohh, now I see how it is, davent. 'let's make arse do all the typing and linking and searching', eh? fine!

[davent]

I'll give you the night shift and i'll take the day shift that way we shouldn't overlap.

[duck_arse]

what time is it now?

[davent]

Your post shows 11:01AM Sunday, presently almost 11:25AM EST Sunday so night shift to me would  in fact be day shift  for you and vice versa... at least in my guessing of time difference between here and Australia.

What time are you now, is it Monday?
dave

[duck_arse]

it is now 01:53 in the blessed am, monday.

[davent]

Alright, 14 hours ahead, time, i would imagine to wish you a good nights sleep. First day of fall here and worse to follow, lucky you, you have summer to look forward to! Good night!
dave

[joeychickenskin]

Thanks for all of this info guys, it solved a couple of problems.

I went with battery only for the SHO to keep things as quiet as possible however using some of the filtering advice I filtered another pedal (Foxx Tone Machine) that had horrendous AC noise and can't really tell the difference between the battery and filtered dc jack.

I also got to test an earlier build SHO where I put the noise down to having deliberately picked physically massive high-voltage components so that, and I'm embarrased to type this, they would look good as I'd built the SHO on tagboard 

I now know that that build works but just doesn't sound as good.

This is a great forum, thanks again!

JC