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 Substitution Boxes

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Join date : 2010-11-22

PostSubject: Substitution Boxes   2018-01-14, 5:54 pm

From time to time, many of us find a sub box would be helpful.
 There are several types I am aware of:
Capacitor- Fixed and electrolytic

Basically, they are all built the same. A rotary switch picking out a certain value of Resistor, capacitor, diode, etc.

 Now, New rotary switches are getting a bit hard to find these days, with the correct number of poles and wafers on them.

I have seen sub boxes using slide switches to switch components in and out to makeup series or parallel rigs to get a certain value.

 Many of the Kit type boxes are aging- over 60+ years old and the internal components are defective. Leaky/shorted/ open paper & 'lytic caps. & way out of tolerance carbon resistors. (Yes, you can rebuild the swap meet /hamfair ones too.)

 Not to mention switches fail, fall apart, break, and the contacts can burn, rendering the switch useless; and I have even seen them abused so much the contacts welded themselves together!

 So I propose a different idea.

Take a project box, mount different colored banana plug sockets (Or for the folks across the Pond- Wander Plug Sockets) on it. The different colors just make it easier to remember which one you are using. (And help assembly under the chassis too).
 Attach the desired components inside the box. Then you can use banana plugs of the stacking type, to get whichever combination of parts/ values you need. Heck, you can even use this idea to make selectable networks!
  The other advantage to this is you can install whatever parts you want. If you commonly use only certain resistor or capacitor values, you may not need but a few parts.
 You could easily build one for diodes, inductors, variable capacitors, pots, etc. also; or any combination.
 For resistors I would recommend using 2W flame retardant types, and for fixed caps, the 630V mylar types. For electrolytics, use good quality 105C rated ones. Be sure to double check and mark on the equipment the polarity and VOLTAGE rating. Capacitor shrapnel can hurt you. Embarassed  I have that tee shirt. (OK, so which end was + again? I think this...BANG!!!!).
  Marking values and polarity, wattage & amperage on your box is a good idea. I have seen many old Eico, Heath, etc boxes with burned up resistors in them.
A diode box could be handy too. Maybe a few Zeners, regular diodes like 1N4007, (You don't need to bother with any of the 1N4001-6 types, the 1N4007 is rated at 1A, 1KV), 1N5408, etc. Maybe a couple of different types of bridges- and be sure to heat sink them too!.

Now I did build a fuse sub box. It was simply a box with a covered fuse holder on it. A few clips held various commonly used fast blow fuses (AGC) I used, as well as some of the Slo-Blow types (MDL).
 I could grab the fuse I needed and pop it in the holder and I was ready to go. It was great for working on TV & stereo sets, and I even had one with resettable circuit breakers on it.

 OK so now you are ready to build your box(es).

Wait, You forgot the most important thing!
Be sure to test your parts before you install them. There is nothing more frustrating than building a great project, only to find out that the " Brand New " part you put in it is way out of spec.

So grab the 'ol soldering iron & get to work!
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Cliff Jones
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Join date : 2010-11-22

PostSubject: Re: Substitution Boxes   2018-01-15, 10:28 pm

Let's Help out Here fellas, by providing places to obtain the parts, such as suppliers of what you need.
Its gonna take some time to gather, then assemble.
Be sure and get quality if you want it to last.
Of course, if you have a scrap Bin all the better, or get yourself to the chat section or post what you need In the trading section. When You do accomplish a project go ahead and post it.

I'm a Science Thinker, Radio Tinkerer, and all around good guy. Just ask Me!
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Join date : 2010-11-23

PostSubject: Re: Substitution Boxes   2018-01-20, 2:29 pm

Never thought of a diode box. That's not a bad idea. Smile
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