curve tracer

Hi all,

Long time lurker, first time poster here. I have been messing around with some electronics lately (synthesizers particularly) and after doing some research, it seems like a curve tracer would be a good investment to help me figure out differences between some of the components I’m working with.

I’m not super-familiar with electrical engineering but I’d like to learn more (more at the hobbyist level), and most of the devices on ebay are waaaay out of my price range. Does anyone know where I can get a good curve tracer? What sort of specifications should I be looking for? Some of the devices like the Tektronix seem uber-complicated, while others seem really simple with only BNC connectors.

Can anyone provide some input?

Much appreciated.

Do you understand what a curve tracer actually does?
Very few modern electronic circuits require the builder to sort components using a curve tracer, and any circuit that did would be considered a bad design.

If you want to understand more about transistors and diodes, then a curve tracer might be useful, but if you just want to build circuits, I don’t see it being very useful (I haven’t used one in 30 years…).

If you really want to play with one, here’s a simple schematic to get you started:

This site may be more useful to you than a curve tracer at this point. I used a curve tracer in school but haven’t seen one since.

I build analog synthesizers, and there the minute specs of a component are very important since everything changes the sound. More importantly, I use rare/old/expensive transistors that are sometimes counterfeited. So, a curve tracer would come in real handy.

To echo what others have said:

I’m a working electrical engineer. I have designed literally hundreds of transistor circuits over 20+ years. I haven’t used or even seen a curve tracer since college.
Curve tracers represent the vacuum tube legacy of electronics.

Vacuum tubes had fairly consistant characteristics. You could count on this, and design each stage to get the most out of each expensive tube. When the tubes aged, the parameters changed, the circuit malfunctioned, so you tested and replaced tubes 'till it worked again.

When transistors came along, they varied so much from unit to unit that the old tube designers had to measure each one in order to use the designs they were used to. So in the early days of transistors, curve tracers were fairly common.

Even then these circuits tended to run into trouble when the circuit got hot, as the transistor parameters are very temperature dependant (unlike tubes).

Eventually designers developed techniques based on (negative) feedback that allowed circuits to self compensate for the wide variations in transistor parameters, and maintain stable operation at temperature extremes.

The techniques tend to reduce the gain of each stage, but transistors became cheap, so you just add an extra stage or two of gain.

Some types of circuits depend on having two (or occasionally more) transistors with matching characteristics. You can use a curve tracer to select them, but you can also buy ICs with closely matching transistors on them. This can perform even better, because they stay at the same temperature.

Companies that make and develope new transistors still need curve tracers to characterize them, and to verify that products meet spec.

Another electronics professional here. If you’re planning to put money in equipment, skip the curve tracer and get yourself a decent oscilloscope. A good 'scope is FAR more useful than a curve tracer; like the others, I haven’t used a curve tracer since school but I use an oscilloscope all the time.

There seem to be devices used for “Analog signature analysis” that are pretty similar to curve tracers:

And the devices to do this are actually considerably cheaper and more available.

See my link, post #2

I designed electrical/electronic stuff for 10 years. During that time I never used a curve tracer. Used a lot of other things. But never a curve tracer.

Three years ago I began working in an electronic failure analysis lab. Now it’s the opposite; I rarely use an oscilloscope, but am always using a curve tracer. A curve tracer is one of the most important pieces of equipment in an electronic failure analysis lab. We have two of them: a Tektronix 576 and a Tektronix 371A.

Because our curve tracers are getting old, we’ve been thinking about replacing them. I haven’t done a ton of research, but I think one of the following should do the trick:

  • Agilent B1500A Semiconductor Device Analyzer
  • Agilent B1505A Power Device Analyzer / Curve Tracer
  • Agilent 4155C Semiconductor Parameter Analyzer

I’m leaning toward the 4155C.