Welcome to the first in a series of posts where I will highlight a specific technique I have learned and instruct you on how to to the same yourself. This first one is on pitch-bending tape recorders. There a couple ways to go about this, but i’m just going to outline my preferred method here. Firstly though, here’s a list of what you will need to do this project.
1) A soldering iron/solder and some experience in using it. Radioshat ones are ok, but usually have a very large tip, all will be much easier if you get a nicer pencil tip iron from one of your many friendly online electronic parts dealers.2) A cheap walkman. The one pictured cost 5 bucks. Go to your thrift store. The early nineties models are great and really simple.
3) Some hook-up wire. Either get it at Radioshat, or if you like scavenging stuff, buy and old parallel printer cable, cut off the ends, slice ‘er open and harvest the wire. It’s typically multi-colored, stranded, and thin, all good things. Plus you can get like 36 yards of it from one cable, that costs fifty cents at the thrift store. Not bad.
4) A potentiometer, or pot for short. This is a bit more difficult. If you are not already an electronics nerd like me, you probably don’t have 100 different kinds of these just laying about, so you will need to get one. Hopefully you have something better than Radioshat near you and you can go and get a few different types for cheap, or, search for grab-bags on ebay. If you are anything like me, this will not be the last electronic project you do, so the leftovers will come in handy. The unfortunate thing about this project is that the pot you will need is entirely dependent on the walkman you have. The general range I have seen in pot values between walkmen, is anywhere from 2k to 10k. If you can’t find out, I’d go for 5k and hope for the best. Or if you happen to have an multimeter, you can measure what size you will need.
5) Some kind of drill. A dremel would be best as they tend to have a bunch of bits, which is handy, but you could get by with a regular drill.
6) Wire strippers/cutters. You can get by without these, but it will be easier with them.
7) A desoldering system of some sort. I use a solder-sucker from Ratshat, but you can use whatever you like.
Ok, lets get started. Firstly, you will need to open your walkman. If you chose your subject well, removing the back panel from the walkman will expose the circuit board, solder side up, like the drawing below.
Once you have exposed the circuit board, look for a pattern resembling the three solder points (yellow dots on the image) in the highlighted area above. They will always have a hole in the center of them, as shown, and if you look through the hole you will see an object with a small slot, the size of a mini screwdriver blade in it. This is a miniature trimmer pot. Those three points are it’s three legs, which correspond to the three legs on a full-size pot.
Desolder the mini-pot and remove it from the board. You will most likely need to remove the circuit board to do so, so be careful that in doing so you don’t dislodge any important components. Once you have dislodged the mini-pot, examine it closely to see if it has any indication of it’s resistance printed or stamped on it. This marking could be extremely small, so look close. If you do happen to find a marking, take note of it, and if you can, buy the same value for your new full-size pot.
Now you will have three empty solder pads on your circuit board. Cut three 5 inch or so, pieces of wire and strip an eight of an inch or so of the shielding from either end. Twist the ends some to “braid” them tight, and then coat them in solder. This will ensure a solid connection to the board. Now, insert the end of one of the bits of wire into one of the holes and solder it to the pad. Repeat this for the remainder of the wires. You should now have three bits of five inch wire sticking up from your circuit board. Take note, or mark the wire that connects to the furthest of the three solder pads from the others, this will be the middle lug of your pot.
Side note: Sometimes one of the solder pads has a resistor connected to it. If your walkman has one of these, test bypassing that resistor and soldering in front of it in the series, instead of directly to the corresponding solder pad. On walkmen that have had this feature, I have found it to greatly increase the pitch range of this mod. I’ve had some that had a speed range from nearly “fast-forward” speed to barely moving.
Now that we have established connections to the board for your pot, we need to find a good place to mount it. This can be quite tricky depending on what walkman you have. I have found that often the cheaper the walkman, the less sophisticated the circuitry, the more room under the hood. You may have to get creative with your pot placement, but be careful to check that when the pot is in place it is not inhibiting any of the other functions of the walkman. I can’t tell you how many times i have installed pots and then realized that once they are in there the case can’t be closed. Trust me, it’s a bummer.
Once you have made a place for the pot, solder the three wires to the three legs of the pot. It will help to make a solid connection, if you first coat each leg of the pot with solder. remember, that the wire coming from the furthest solder pad from the rest (the furthest right in my image) gets connected to the center leg of the pot. The others can be connected as you like, but i usually like to make it so that when i turn the pot right the motor speeds up and when left, it slows.
Now that your pot is connected and functioning, mount it in the spot you made for it, and seal the walkman up. Congratulations, you just pitch modded a walkman!
For even more fun, you can do the same mod, but instead of using a mechanical pot to replace the trimmer pot, you can use a photoelectric cell. If you have never heard of one before, they are potentiometers that look like very small solar panels and react to light. They sell these as grab bags at Radioshat. If you’d like to try this, it’s a bit easier that modding with a mechanical pot.
To use a photocell, just connect one leg of the photocell to the solder pad furthest from the others in the pic I posted and the other leg to one of the other of the three points i highlighted. Only one will work, and it depends on your walkman which it is, but there are only two options, so I’m sure you’ll figure it out. This kind of mod makes a sort of tape driven phototheremin. Record some tape loops of drones and play it by using your hand to shade the photocell.
This concludes our first Primer, I hope someone out there finds this useful. Please feel free to ask questions in the comments if something’s not clear.
Oh, and of course there has to be a sound sample! This is a few tracks of various tapes being played on the pitch-bent walkman that I layered up. Enjoy!
– Pitch-bent walkman