You wrote.... Your impression is correct. However, faster is not always as elegant. Utter sacrilege. Can you build some type of pigtail cable instead? By the way... a day or two ago, I came across an EC-1 on ebay that was labled in such a way that I doubt people would find it with searches. Don't remember how. At least, I seem to recall that is what I saw.... Jay

Hi I've seen several sites that offer Heathkit manuals. Some of them originals. The EC-1 is good for doing linear differential equations ( converted into integral equations ). It does lack the ability to multiply two analog levels. All scaling is done with fixed or adjustable resistors. The operators manual has little in it other than simple examples of adding signal together and integrating with capacitors. It does have an interesting simulation at the end. It is a bouncing ball simulation. Such things as gravity, bounce lose and air friction can be fiddled with. It does require an external source for a sine/cosine source to create the ball on a scope. One could create a sine/cosine source with two op-amps but the ball simulation requires all but one of the EC-1's op-amps. A while back, I wrote down a solution that reduced the number of needed op-amps by one. This frees up the needed extra op-amp to do the oscillator. I put the schematic some place but I believe most anyone could figure it out with a little thought. One thing to be aware of is the offset adjustments. When using the op-amps for gain and inverter, you adjust it slightly different than what you'd do for integrators. In one case you are balancing offset voltage and the other offset current. The original used the half the clear plastic connectors that used to be used to connect 300 twin lead. RS used to carry these years ago but I've not seen any anywhere. These had the right spacing to work with the crystal sockets used on the front of the EC-1. I've fount that the mini-banana connectors that Pamona has ( see their web page ). Of course, they are a source for the needed standard size banana jumper cables. These are not cheap but they do have them. I think Doug Coward's site does have the schematic for the bouncing ball simulation. That is the most important part of the operators manual( I think it is still someplace ). Dwight