Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives Magazine Sponsor RF Cafe Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Alliance Test Equipment Centric RF Empower RF ISOTEC Reactel RF Connector Technology San Francisco Circuits Anritsu Amplifier Solutions Anatech Electronics Axiom Test Equipment Conduct RF Copper Mountain Technologies Exodus Advanced Communications Innovative Power Products KR Filters LadyBug Technologies Rigol TotalTemp Technologies Werbel Microwave Windfreak Technologies Wireless Telecom Group Withwave Sponsorship Rates RF Cafe Software Resources Vintage Magazines RF Cafe Software WhoIs entry for RF Cafe.com Thank you for visiting RF Cafe!
withwave microwave devices - RF Cafe

Noisecom

TotalTemp Technologies (Thermal Platforms) - RF Cafe
KR Electronics (RF Filters) - RF Cafe

Transistor Substitution Box
February 1960 Radio-Electronics

February 1960 Radio-Electronics

February 1960 Radio-Electronics Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Electronics, published 1930-1988. All copyrights hereby acknowledged.

There aren't many people using transistor substitution boxes these days because circuit simulator software is readily available to reasonably predict which type will serve the intended purpose. However, back in 1960 when this article appeared in Radio−Electronics magazine, substitution boxes for not just transistors, but also capacitors, resistors, and sometimes inductors were used quite often when prototyping and/or troubleshooting circuits. I used resistor and capacitor substitution boxes all the time in the early and mid 1980's while working as an electronics technician at Westinghouse Oceanic Division, in Annapolis, Maryland. That was my first place of employment after separating from the USAF. Prior to moving into the engineering lab, I built electronics assemblies for U.S. Navy sonars used on torpedoes, ship hulls, and towed vehicles, including printed circuit assemblies, cable harnesses, chassis assemblies, and piezoelectric transducers. Occasionally, I was tasked to build component substitution boxes for the engineering lab and the test equipment repair / calibration (metrology) group. Little did I know at the time that in the near future I would be using some of the equipment I built.

Transistor Substitution Box

Front panel of the transistor substitution box - RF Cafe

Front panel of the transistor substitution box.
Chart at right shows which transistor is in use.

10 transistors at your fingertips. Just flip a switch to select the one you want.

By Leonard J. D'Airo*

This transistor substitution box has proved to be a pretty valuable piece of equipment on a number of occasions when transistor circuits were being checked out. It has taken a rightful place in my workshop, alongside the resistance, capacitance and inductance substitution boxes.

A transistor substitution box is, of course, much more expensive than the more usual capacitor or resistor substitute array, at first sight so much so as to appear impractical. But until we get a great deal more familiar with transistor receivers and can spot a bad transistor more easily, the positive answers it gives save enough servicing time to pay for it very quickly.

In this unit, there are substitutes for 10 transistors. Included are general-purpose, small-signal audio, large-signal audio, power and RF types. Selection is for useful characteristics and any combination may be used.

Circuit of the transistor substituter - RF Cafe

Circuit of the transistor substituter.

The combination shown in the schematic covers most practical applications. These transistors are:

General purpose 2N107, 2N170
Small-signal audio 2N132, 2N214
Large-signal audio 2N217, 2N213
Power 2N256
RF CK768, 2N484, 2N147

Note that in the first three groups, one transistor is a p-n-p and the other is an n-p-n, while the power transistor is a p-n-p (since most applications use a p-n-p unit). In the RF group, two transistors are p-n-p's and one is an n-p-n.

Inside the substitution box - RF Cafe

Inside the substitution box. Author used transistors other than those in the schematic and listed on the box's front panel to match his own special requirements.

The transistors suggested in the parts list represent the average units used in transistor radios, amplifiers and related equipment. The types that are finally chosen and used should match the particular requirements of the user.

A cigar box or aluminum chassis box can be used to mount the selector switch and transistors. All wiring must be quite rigid and as short as possible. The power transistor must be mounted on a heat sink and kept as far as possible from other transistors.  

* Author Servicing Transistor Radios, Gernsback Library.

 

 

Posted February 23, 2023

Rigol DHO1000 Oscilloscope - RF Cafe

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright:
1996 - 2024

Webmaster:

Kirt Blattenberger,

BSEE | KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

Copyright  1996 - 2026

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website: AirplanesAndRockets.com | My Daughter's Website: EquineKingdom

Windfreak Technologies Frequency Synthesizers - RF Cafe

Werbel Microwave (power dividers, couplers)

Anritsu Test Equipment - RF Cafe