Dirty Tricks

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.

Anything worth doing is worth doing confusingly

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.

Parts are not always what they say they are.

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.

There are four classes of dirty tricks parts:

  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:

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:

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

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

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.