A trip to Radio Shack will get you the piezo and 1/4 inch mono jack. They are in a drawer case towards the back of the store and most stores usually have them in stock. The piezo you are looking for is the 273-073 and costs 2$ and the jacks are #274-255 and are two for 4 You can also pickup a 25 or 30 watt soldering iron and some fine(thin) rosin core solder here or go to Harbor freight and save some money. Its all chinese junk anyway. If you use a damp paper towel or sponge and keep the soldering iron tip clean it will last a fairly long time.
Keep it tinned (heat the tip and run some solder on it before soldering) Cheaper and easier to wear out a cheap iron and replace unless you're going into business. Do NOT tighten up the little screws on the barrel too tight as they hold the heating element in. Do not remove these screws and pull as it will junk the iron. (common mistake) Give the iron lots of time to heat up. It might take it ten or more minutes to come up to temp. This is normal for a low watt iron and you certainly don't need more watts. Too big an iron will burn the insulation off and melt plastic not to mention stink. Speaking of stink, ventilation is good as the fumes are not very healthy to breathe. (just a small fan blowing across you will do the trick)
If you go to Harbor Freight you can pickup a "helping hand" for only four bucks. (11$ at Radio Shack) and also save considerable on the solder and soldering iron.
Here are the URL's
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47887
soldering iron 5$
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95861
solder 3$
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=319
Helping Hands 4$
The 273-073 piezo comes suspended in a plastic case as its original purpose is to be a buzzer. Since we want it to pickup the sound from our guitar and send it to our amplifier it needs to come out of the case. I have put together a picture story line to illustrate this. I take a pair of pliers and grasp the ear on one side of the case -squeeze and snap the ear and a piece of case off. You have two ears so two chances to get a good hole in the box to pry the top off with. I insert a pocket knife tip or small screwdriver in and slide it right under the plastic top so it misses the piezo completely - then pry the top up and it will pop right off. Careful the Piezo is suspended in there but its close to the top. Then stick a blunt small screw driver in the hole in the bottom of the case and gently push up. The piezo will pop right out with very light pressure. DO NOT BREAK IT by applying to much pressure. Easy does it. Now you can strip the insulation off the wire back a bit and twist the the strands into a single smooth wire. Insert it in the jack and twist it up tight so there is a half decent mechanical connection black goes to the center ring ground terminal on the jack and red goes to the lug that leads to the tall center pin part. Once twisted up tight plug the iron in and let it heat for ten or fifteen minutes. Tin the tip by melting a small amount of solder on it. Stick the tip in the hole on the jack and wait a few seconds then touch the solder to the tip where it came thru the hole and or to the wire itself. The tip heats up the parts to be soldered and then the solder "runs" up the wire and into the joint. If its done correctly it will all be silvery smooth and fairly quick. If the joint is not hot enough you will get a cold solder connection which is BAD. You do NOT melt the solder and drip it onto the wire or terminal. If the wire and terminal are hot enough the solder wicks up the wire as it melts - nice smooth and strong. Its not necessary to add wire to the ones I have built nor to put any switches in the circuit. I mount mine to the neck as it goes thru the box close to the bridge - I use foam mounting tape that sticks the brass side of the piezo to the neck - I use two pieces side by side to get it wide enough and then cover the top with two more pieces side by side to cover and buffer the piezo. This makes a nice clean installation and its extremely strong. Its also really buzz free. The foam mounting tape is double sided "Duck" brand 3/4 inch by 22 ft and 1.5 inches holds a quarter pound. Mounting the jack to the box typically makes me drill two holes - a larger one half way thru the box then a smaller one all the way thru. I have not had good luck keeping these tight enough yet and intend to use gel super glue liberally on the next installs to see if that will help.
When I get time I will put together another blog to illustrate how to double these piezos up reduce the impedance to closer to what a standard amp wants to see. Basically they are wired in parallel so that each set of leads goes back to the jack - so it would be a pair of reds and a pair of blacks coming back to the jack to use double piezos. Series doubles the impedance and parallel halves it. Parallel has a very desirable reduction in impedance. Another subject worth exploring is shielding the leads by wrapping copper foil around the wires and grounding back to the ground lug. This stuff is a bit tricky and care needs to be taken not to set up any ground loops. I need to take more pictures to correctly illustrate this.
Hope this all helps with any amateur soldering and piezo destructing. Comments and questions welcome - Bill
Piezo in plastic buzzer case also removed from case - brass side and ceramic side shown. This is what we want.
And off pops the top. There is the piezo ceramic side up - brass side down. On the other side is a hole to let the buzzing sound out. Perfect to stick a small dowel or screwdriver in and nudge the piezo up. Gently!!
A gentle push up and there is the edge of the piezo, finger food now.
The prize - a nice piezo transducer with leads factory soldered on . notice the red positive goes to the ceramic and the black ground goes to the brass base ring
Jack with leads from piezo soldered on . The black goes to the center ring - these solder joints are too large and would make an electronics tech sneer but they are well done and solid connections if not pretty. You can do this well with a minimum of practice. It works!
Comments
This is easily one of the most well put together tutorials I have ever seen on the internet. Perfect amount of detail. Helpful links that work and Great pics. Well done. I can do this and will. Thanx so much for your time and effort put into this.
Jon - the mounting tape is double stick adhesive - 3M I think and any office supply store has it. Staples or similar. Its usually used for sticking posters up I think. Its got really good adhesive and pretty dense foam. It works well to buffer the inexpensive piezo's
Installing a 1/4 inch jack is pretty easy but requires two forstner style bits for most of my builds. Thicker cigarbox bodies need to be bored half way thru (more or less) with a bit that will allow the jack body to recess into the box. Then finish with a bit that just is large enough for the threaded part. Set that nut down TIGHT with some needle nose pliers if you are going to glue the box lid on - can't tighten it later. I usually tighten it tight then just before gluing snug it again. Recessing the jack makes a nice clean installation. I usually don't put volume control or on/off switches on mine. Plug it in = on Turn the knobs on the amp = control. Simple.
Hey -Jim - glad that worked so well for you !!
Thanks for posting this detail Bill! I was just finishing up on my first build and thought I'd have to wait to add wiring. I was looking for simple on this first one. With your detail I jumped over to Radio Shack, bought the parts, and had my CBG wired up and playing within half an hour!
Reply to Dan David - Yes peizo's need to be wired in parallel. They are very high resistance and wiring in series adds more resistance and parallel does the opposite in effect. Plus if one fails in parallel the other will carry the day. I have wondered about using a string of four or more on a harp stringboard - will try it one of these day. I did wire two in series once as an experiment. It works as a pickup but requires much more volume control on the amp to get the same sound. It just doesn't seem "right" somehow. But it did more or less work. Parallel is THE way to go.
Reply to Hank S - I simply lay down two parallel strips of 1inch wide tape on the neck - as it goes thru the box. I put my piezo's as nearly under the bridge as I can. Then peel the tape release liner off leaving a sticky surface. Place the piezo or piezo's on the sticky and then cover with another pair of parallel strips. All this is done in a bit of a recess in the neck so that they can not touch the back of the soundboard. I bandsaw out the whole top of the neck inside the box so that there is almost a quarter inch of clearance. I then reinforce the back of the neck with a strip about 3/4 inch square to compensate for the removed material.
I haven't built much of anything lately, I am working on four different designs - and a bit of a marketing strategy. I am actually waiting to see how the election turns out. If we are facing four more years of the same I will NOT build anymore than for my own fun. If we get a chance to go back to prosperity with R/R I plan to rebuild my shop and have some fun building piles of new things. You are right about needing pictures and if/when I build I will post new pics to supplement this. Thanks Bill
could/will you show pictures of how you mount the piezo element in the guitar with the foam tape? thanks. what about using super glue to do the same thing? thanks again.
Jim
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