A couple of handy circuits for driving LED & opto-couplers.

When trying to work out a solution for driving a Vox wah circuit automatically, I found a handy pair of circuits by one Mr Bill Bowden.

The site is no longer active, but I managed to find a copy on Web Archive and later Bill's new website

There are a number of flashing circuits based on 555 timers and both Dual & Quad Op Amp designs.

I've extracted the two images that I use the most and have been particularly good with Tim Escobedo's PWM and the above mentioned wah circuit.

The resistor between pins 7 & 2 controls the rate.

I have used TL072 & 4558 chips in place of the 1458

According to Bill's website, it can also be used as a straight up LFO without the LED and is good for up to around 10khz. I haven't been able to get it to drive an LED faster than about 1/3hz yet, but that's due to a lack of time & actual knowledge of electronics on my part (you don't need to know much theory in order to tinker with FX pedals & synth circuits).

Fender Pawn Shop Bass VI - Review 2013

I've had this instrument for about 6 months now, and overall am very happy with the purchase. Though it isn't without its issues.

Its been so long since I purchased a box-fresh instrument that I can't really compare to my previous (twice?) experiences.

I was prepared for a couple of issues by the multitude of forum posts around the web.

Namely these:

• String Gauge
• Intonation
• Setup
• Crackling electronics
• Aesthetics

The first three points are all related, so I'll tackle them together.

I opened the carton in store, so it was about as fresh as one could get.

The guitar was more or less in tune, but a little lower than standard pitch which I imagine was intentional for shipping purchases. 

As far as setup goes, the guitar was assembled with the neck straight enough to play. The action was fairly low, but as expected (and experienced on the floor model) the low E buzzed like a nest of bees living in the chimney (true story from my childhood).

The vibrato was not setup. I suspect the same issue was the source of one uneducated complaint on the internet that I saw regarding the height of the vibrato bar from the body. Indeed it was too low to play. But easily corrected with a couple of turns of a screwdriver.

Once I got the Bass VI home I attended to the intonation. For the stock action it was pretty close already, but as forewarned by the elders of the internet, the low E would not intonate  without modification to the bridge.

One extreme I saw, was drilling a hole from the neck side of the bridge and inserting the screw that way. My solution was simpler.

Remove the long saddle screw & spring and use a short screw with no spring.

The saddle needed to be right up against the tail side of the bridge, but did indeed intonate spot on, but the string still buzzed.

I did manage to get the buzzing to stop by raising the action a bit, but that meant intonation was not going to happen. Simply because the bridge (not the saddles) is far too narrow for the scale length.

Surely Fender could make a stamped metal bridge cheaply for this instrument?!?!?

Anyway it is likely that I'll be upgrading to a Staytrem as they make a 1" version which is suitable for the Bass VI and apparently without any major surgery. That will have to wait a bit though as I have other expenses at the moment.

This brings us to the crackling.

It seems that a corner was cut in production. There is no foil backing on the pick guard. This causes the pickguard to act like a capacitor which discharges slightly as the instrument is played.
The foil tape is so cheap. I find it absurd that it was left off the instrument. I'll be adding it to mine once I get around to changing the strings.

I get that the idea behind the pawn shop series is that they're meant to be different to what has come before. The instruments in this range look great, but a lot of people are ticked off that this instrument has a distinct lack of chrome.

I don't mind that its pickguard is a little different. For me its like the difference between a Jaguar & Jazzmaster. For that matter I don't mind that it has a Jazzmaster shaped pickup in the bridge (or that its really a humbucker).

What I don't really like is the blade switch.
Especially the knob. It just doesn't look right.

I would have made one of two changes if I were on the design team. Either A: Slider switches in the plastic pickguard or B: a chrome plate for the 5 way switch like on the Johnny Marr Jaguar.
I'd also add in a 3 way toggle like on the Kurt Cobain Jaguar (though having photoshopped it from stock images, I'd go with option A) .

Although there are a couple of things that could have been done better, they re really quite minor.

The neck, though big and chunky actually feels really nice in the hand and is very comfortable to play (have smallish hands). The finish is superb. Its pretty tough too as I've bumped it on my concrete floor a few times and it didn't leave even the slightest scratch.

The pickups are supposed to be wound hot, but seem like they're actually rather low in output. That's fine with me as I prefer lower gain in general. The sound from Neck and Middle is excellent, but like most people seem to be, I'm not too keen on the bridge.

That said, I usually play all of my guitars on the neck pickup so maybe I'm just biased?

I really like this guitar/bass thing.
The only problem I have with it, is that all of my other guitars now feel like toys.  I'm having trouble going back to the Mosrite the most, because the necks and string spacing are vastly different.

Actually this goes for all of my other guitars.

Six months on and I'm still pleased as punch.

Jim Dunlop - Octavio

Octave Up effects don't suit everyone.

In general chords just sound horrible and the effect is really only noticeable round the 10th to 14th frets. Some people disregard it as a one-trick pony, and in a way I agree.

I've built a few Octave Up pedals over the years, some I've kept, some I've sold.
Honestly I can't even remember all of the pedals I've made & parted with.
Pretty sure I built a green-ringer once upon a time.

Don't remember selling it or destroying it, but it isn't in the arsenal any longer.

Anyway, my point is, I like the effect enough to keep building variants, but my favourite is the cheese wedge of the Jim Dunlop - OC1 Octavio.

The Octave Up is clear and distinct for about 90% of the Fuzz range, then you hit this tipping point where the Fuzz is really intense and the octave becomes really dirty. It is a pretty loud pedal and has a tendency to clip the input of any buffered bypass effects in the chain.

I've mostly played it with a  regular 6 string and it has been an enjoyably noisy affair, but recently things have taken a turn to the lower end of the range as I have acquired a Bass VI.

I used to think that it would only really suit the 12th fret region on a regular guitar, so never bothered with a bass instrument. I was wrong and I was missing out. The Bass VI produces the octave effect very clearly when playing reasonably calmly, but start going a bit silly and every note distorst in a way that evokes an auditory image of a torn speaker.


Try running it with a nearly exhausted battery. It does gets into synthesizer territory.
Hmm... I think I might need to build a flat battery simulator soon.....