TGIMBOEJ

The Great Internet Migratory Box of Electronics Junk or TGIMBOEJ for short is the reson I have started this blog. It is basically a box (now many boxes) full of eletronic treasures from other people’s junk boxes. When you recieve it in the post you take out anything you think you could use and replace with items from your own junk box that someone else might have a use for. Then you send the box to one of the other people on the recipient list and on and on it goes. Well that’s how it is supposed to work.  The TGIMBOEJ was started by evilmadscientist and you can add your name to the recipient list or start a box by going here.

I only read about this on evilmadscientist recently and thought I should start a box of my own. There are not many people in Australia on the list, but I always have too much treasure lying around the place. I threw together a shoebox full of stuff that could be usefull to the electronics hobbyist, took some pics to document it, and started this blog. Now I am starting to wonder if it is worth going to the trouble, I have been reading some of the other blogs and it seems a lot of the boxes that get sent out don’t get passed on and just dissapear.  I might as well try and finish what I started though, and hope this box at least makes it past the first recipient. I have messaged Matt on the recipient list in Australia and he has emailed me, so the box is going to him first.

So what’s in this box I keep going on about? Well theres some old school valve gear in there, this is an area of electronics that I am into so I hope someone else will find that stuff useful.  Then there is the usual assortment of bits and pieces, some new components, some puled from other items and projects, and a few broken consumer items. Have a look at the pics to get an idea, it would be great to see some of this gear used in a project.

An old meter and some largish capacitors, the blue mallory cap is 80,000uF.  The  meter works fine but will need 2×9 volt batteries.

 

 

 

 

 
 
floppy drive from apple laptop, old nokia not sure whats wrong with it, the dopod PDA type phone was working fine until the screen was broken. I think the LCD is from a sony digital camera.

 

 

 

 

PS2 remote and psone reciver module, they work together on a psone. Conroller, 9v plugpack, mechanical counter from an old reel to reel? other stuff.

 

 

 

 

 

 

Small perfboard and a piece of single sided copper clad board. I have put in about a half sheet of press’n'peel in case someone has been wanting to try this stuff out.

 

 

 

Decatron tubes, two different types ( 2 of each) and the sockets for them. These haven’t been tested but they look OK.

Tubes, 12AT7, GSN7, EF95, EC8F80, EZ80. None tested (I don’t have a tester)

 

 

 

 

 

An assortment of stuff here, ICs, chip amp, sockets, switches, photo interupters, some new some old, a lucky dip of components.

 

Pots and more pots.  A couple of vintge switched pots,  A photo flash unit. I am having trouble getting those 2 radio tubes into the box safely, it’s getting full, they might end up going into a future box.

 

 

 

A couple of guitar effects built on veroboard. The small one is a fuzzface and the other is the ampeg scrambler. Click those links for the circuit details.

 

 

 

 

Well that’s about it, if you think something in this box or one of the other boxes would inerest you, get your name on the list. I might make another box up later on, I am in the process of building a new shed/workshop, and I’m sure there will be of stuff uncovered in the move. If you do use something from this box in a project, please put some pics up and let me know about it.

 

I forgot to add this earlier, but I have posted the box to Matt, who is on the recipient list.

Variable dual power supply

I needed a variable dual power supply for my workbench which could deliver around 1.5 to 30 volts at around 500mA. There are plenty of designs on the net but decided to do one from scratch so I could make the most  use of what I had on hand. I pretty much decided from the start to use the LM317 and LM337 adjustable voltage regulators, I had used them before, they have good in built protection and they would do the job and they were in my parts box. If you use this design you will only be able to go down to about 1.2V because that’s the minimum output for the voltage regulators. If you want to go down to 0V you can put a couple of diodes in series with the output of the regulators, the voltage drop across them will get you down to zero but just be aware that you will lose a couple of volts from your maximum voltage.

I drew the schematic and did the board in eagle, nothing fancy here, looks like a hundred other circuits using these regulators, I made sure it should have pretty good filtering of the DC output and the PCB would fit easily into the case I was going to use along with the transformer. I have included the PCB pattern in case someone wants to etch their own. Of course if you are not experienced and comfortable working with mains voltages, you shouldn’t build this without assistance from someone who is. Make sure the mains earth wire is attached to a dedicated  secure point on the metal enclosure, scrape off any paint or other coating to ensure good contact. A correctly rated fuse on the input is a good idea, I included a panel mounted fuse holder and 240V power switch on the rear of the case.

PCB pattern correct orientation for toner transfer method

component placment overlay

 

If you do want to build your own a couple of points to be aware of:

TRANSFORMER
 The transformer obviously has to meet your voltage requirments eg. if you need a maximum of -12 to +12 volt output, you will need probably a 30V centre tapped transformer (-15 -0- +15), you need the extra voltage to allow for the voltage drops accross the diodes and the voltage regulators need a few volts higher input than you want output. You don’t need to change anything in the circuit to use these slightly different output transformers. I’ m not sure of the specs offhand but I wouldn’t go any larger than a 60V 2amp transformer with this setup and that is probably an upper limit.

 

CAPACITORS
The value isn’t critical so if you have something close it should be fine, use your best judgment here eg. instead of 2200uF you could use 3300uF or 4700uF. Yes there are quite a few and there are plenty of designs which use less, but I wanted a nice supply for testing audio circuits.

RESISTORS
Stick with the values listed if you are going to use 5k pots for adjustment. It is the combination of the resistor and variable reistor (pot) on each regulator that determines the output voltage. You can fix the voltage at a desired output if you don’t want it variable by using another fixed resistor in place of the pot. Calculating the output voltage is simple using an online calculator like this one. Instead of using pots, you can use fixed resistors soldered to a rotary switch to give you selectable voltages. The standard 24mm carbon pots are 

VOLTAGE REGULATORS
You will need heat sinks on the regulators because they are going to get hot. Of course the more you try to draw from this supply the bigger your heatsinks will need to be. You might want to add a fan if you run it for continous periods at decent levels and/or you want to get awway with smaller heatsinks.

 

BUILD PICTURES

not many pics of the actual build but a few of  making the PCB which I will put here also so people can see how using the toner transfer method with common old magazine paper works. I prefer the blue press’n'peel if I am doing fine traces, but the magazine print works great for less critical stuff.

printed pattern onto magazine paper with laser printer, board prepared by scrubbing suface with scouring pad or 1200 grit wet’n'dry paper. Surface cleaned with acetone or use detergent in warm water when you scrub it, then dry well.

 

transfer toner to copper with iron set on highest heat setting (no steam). I like to use a sheet of paper between the iron and the magazine paper. Rub the tip area of the iron over the entire board slowly with firm pressure. It will take about a minute of ironing to transfer a pattern this size, you need to get the borad quite hot.

 

I will finish posting the last bit of this build tommorrow