From: Günter Ritter in Germany

Date:May 3rd, 2005

[snip]

My first contacts with Op Amps was during my study at Marburg Philipps University in the early seventies, when I attended a course/ seminar of the Physical Chemistry Institute. One major part was the understanding and conducting experiments with operational amplifiers, mainly for the simulation of mathematical equations, like addition, subtraction, multiplication and division, e-functions, logarithmic functions and more complicated equations, relations.

The highlight of this course was the use of opamps for so called "analog calculators" which could simulate any physical phenomena and processes. By developing the appropriate opamps with the needed mathematical function plus the required electronic passive components ( e.g. resistors, capacitors etc. as simulating numerical constants ) the combined use of various opamps could replace or simulate any physical process as complicated as possible or as you could think of. Even the Schrödinger Equation and calculations of electron gas energy levels and Eigenvalues were possible. The " analog calculators" produced all values, diagrams, time dependent results as it is possible nowadays using high performance computers, but much simpler and much more precisely, because they worked strictly analog and not digital!

I think these "analog calculators" are forgotten today which is a great pity because they could be powerful tools for the simulation and calculation of any physical processes using the modern solid state, highly integrated opamps available at low costs.

If remember it correctly during this student course we also used opamps produced by Philbrick!! Which closes the circle and which initiated some recall of my student's activities.I still have some minutes, notes and literature, mostly handwritten.

Today my interest in opamps is more focused on HiFi use, e.g. as NF amplifiers, impedance transformers and even in power opamps for direct amplification of NF signals, e.g. for headphone amplifiers and week loudspeaker amplifiers. Since I am a chemist my knowledge in electronics is not highly developed and more on empirical and trial and error level. But at least I understand enough to use a soldering pen and to built simple electronic circuits. ( "NF" means " Nieder Frequenz" or low frequency/ audio frequency signals)

My other passion are vacuum tube amplifiers and I possess quite a collection of German studio equipment from broadcasting studios.

Now the old Philbrick vacuum tube OpAmps are such a wonderful surprise for me and I can see the possibility to combine both interests ( opamps and tube amplifiers).

[snip]

with best wishes

Guenter