Copyright 1999 R.G. Keen. All rights reserved. No permission for local copies or re-serving from other web sites.

Makers of all sorts of things are concerned that the special clevernesses they put in their stuff will be copied by dirty rotten scoundrels as soon as the first unit leaves their door. And in fact, history has proven this to be a valid fear. To prevent this, makers of all kinds of things have been engaged in protecting what has become known as "intellectual property" for centuries if not millenia. Today, we have patents to protect really novel stuff, but for the more pedestrian things like effects circuit that are largely not patentable, effects makers have turned to obscurity, hiding their designs under layers of epoxy or other gook to keep the casual copier at bay.

This works sometimes- especially if the copier gives up easily, but a dedicated copier will go find a friendly veterinarian or dentist with an x-ray machine, or use a rotary burr on a Dremel tool and have his way with the epoxy anyway.

A slightly more sophisticated way to protect a circuit is by duplicity - things that appear to be that which they're not. Having been involved in the highly competitive world of computer production, I'm the only circuit tracer I know of that will take the trouble to actually measure the values of parts as well as look at the indicated values. For instance, assuming you had to connect two stages of a circuit. You could just use a PCB trace - or a jumper wire, or a 10 ohm resistor. If you used the 10 ohm, but covered the black multiplier band with a band of green lacquer, a casual copier would write down "1M" and no copies would ever work right.

Figuring out what is actually going on in a circuit is hard enough when you have a circuit that actually looks like what it is. If it appears to be doing some other equally valid thing, it becomes much harder to understand.

An early minicomputer maker that is now deceased used to use programmable logic chips in their mini's. Instead of simply leaving the original part number on it, or grinding the nubmers off, they re-stamped the chips with the part numbers for common, everyday 7400 series TTL logic chips. Ugly. This was a fundamental step better than simply grinding off the part numbers. Things that are presented as mysteries often inspire people to greater efforts to solve them. It's better if they don't realize that there is a mystery to begin with.

1. things that are good parts, but mis-marked
2. things that are apparently good parts, but deliberately broken in some way
3. things that are not real parts at all
4. things that are good parts, marked for what they are, but doing something no one believes

The first three versions offer some protection against the straighforward copier, as they mislead the copier into making copies with actual good parts that are NOT the same as the thing being copied. A clever and determined copier will not be mislead for long by them. The fourth way is no bar at all to the straightforward copier, but can defeat the clever copier sometimes. However, in doing this, a maker has to bet that they're cleverer than anyone who will ever look at the circuit - and that's like drawing to an inside straight for you poker players.

For Class 1, the dirty trick relies on people to assume that the value marked on the part is the real value or type number. However one is free to use:

• Resistors that are mis-marked; this is easily done by changing the multiplier or value bands. The 10 to "1M" mismarking is one way to do this. Clearly, you can change a 1M to a 10 ohm as well, or other subtler changes.
• A capacitor with the value polished off but re-stamped with the wrong value
• An IC relableled with some new name, or a transistor re-marked to some other name - like maybe an SCR part number.

For Class 2, the tricks can be more creative. Class 2 adds the interesting fillip that a smart copier will even find the "bad" part and fix it. One can use:

• An abused part, like a capacitor you've shorted by exposure to overvoltage; note that some film capacitors can "heal themselves" somewhat, so you have to be sure your creative damage will last or you'll be sabotaging your own goods.
• A resistor you've "drifted" with heat
• A transistor you've exposed to the tender mercies of a 1000uF/200V capacitor that's fully charged. These will fail either open or shorted, and so they have to be sorted after being "charged up".

 In Class 3, for things that never were real parts:

• A conductive capacitor; take a block of plastic or wood, through-drill it with a proper sized hole, insert a continuous wire or a resistor through it and coat it with bright colored epoxy. It looks like an epoxy-coated cap and is instead a conductive link. A determined person would get a stamp made up with some obscure lettering like "105K 100V Mitotyo".
• A tiny block of epoxy cast to look like a TO-92 transistor but with all the leads connected inside the blob. Your imagination can add more to this list, I'm sure.

The opposite works as well - connecting things that must not be connected with parts that don't conduct.

• A wooden or plastic cylinder the size and shape of a resistor with wire leads glued into holes in the ends, and painted to resemble a real resistor
• A wooden or plastic "capacitor" as above with leads that don't connect through.
• A tiny block of epoxy cast to look like a to-92 transistor, but with leads that don't connect inside; perhaps stamped with a real part number as above.

Any of these can be used literally anywhere, as no-connects don't change the function of the circuit at all.

In doing all of these, a maker has to be sure they design the packaging and boards to accept the "creative" part(s) and that there will be an adequate supply of the special parts - which introduces the cost of cleverness. Putting dirty tricks parts on a board costs real money, as the price of a "creative" part is many times higher than the cost of a real one. Worse, it probably can't be handled properly by a commercial assembly house, which is doing good to keep the real parts straight. It adds to warrantee costs, as the maker has to keep repair people informed to get repairs done and also watch to ensure the secret doesn't get out. A side effect is that the maker has to guard against the possibility of getting a reputation for building non-repairable equipment as well, because people will insist on taking their stuff to their local tech in spite of the "lifetime mail in warrantee".

In the end, this does not protect a manufacturer from someone who will take the time to measure and think, and who also has the background to decide the circuit does or does not make sense from the parts that aren't faked. Those people generally have better things to do than to copy and sell effects - which is good, because there is no preventing them from finding out how something works if they have access to it and they really want to. They're rare, but they do exist.

My own personal conclusion is that obscuring the contents of an effect is a costly exercise in doubtful security. I suspect that is why most makers do not use these. But you should be aware of what is possible.