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Transistor Curve Tracer Kit


This curve tracer is built around the kit available from Thaikits.com. It is based on the Elektor curve tracer published in the December 1989 issue of Elektor Electronics magazine.

Picture
I purchased the combo tracer PCB kit and +/- 15VDC power supply kit. All the components on the PCBs are included in the kits except for the extra header pins I added for connecting the switches. All components are installed by following the silkscreen on the boards.

Not included in the kit are the case, power transformer or any of the components mounted to the front and rear panels except the two BNC jacks.

Picture
I built the tracer in a vintage Radio Shack/Archer slope-front case. The case already had some holes drilled in it so I had to plan my panel layout to accommodate them.

Picture
I made only one modification to the tracer PCB. The original Elektor version had a switch inline between pin 9 of the 4024 counter IC and the D/A resistors, to switch between 4 or 8 curves on screen. I cut the trace to pin 9, drilled holes in the trace on each side of the cut, and added a two-pin header for connecting a front panel switch.

Picture
Testing the tracer using my Tektronix 326 scope. The 326 doesn't have a built-in X/Y mode, but it does have an external horizontal input. The X and Y BNC jacks are on the rear of the tracer. On the 326 X goes to EXT HOR input and I connect Y to one of the vertical channels.

I installed two sets of test sockets in the tracer that connect to the PCB through a 3PDT switch. The sockets and banana jacks are mounted fairly close together to keep lead lengths as short as possible (to prevent oscillations). The original Elektor article recommends less than 10cm which is hard to do when mounting the PCB in a case. These leads are longer than 10cm so I added ferrite beads to the socket wiring to help prevent oscillations. With the two sets of sockets I can compare curves and match transistors with the flip of a switch.

Picture
Just for fun I hooked the tracer up to my old Tektronix 321. The display doesn't look too bad, needs a bit more horizontal gain and the curves are reversed horizontally.

Picture
My Heathkit scope has an X/Y mode and displayed the power transistor curves well enough, but the small signal curves were quite noisy. I went through the tracer with a scope checking waveforms and looking at ripple and noise on the +/- 15V rails, but it wasn't until I started checking grounds that I discovered the problem. I had grounded the X and Y coax cable shields to a lug attached to a metal standoff for the PCB. But the power supply and tracer PCB are grounded to the chassis at a terminal strip near the power transformer. Since a single point ground is usually a good idea, I pulled the coax shields from the standoff solder lug and grounded them at the power supply ground. And magically the noise completely disappeared. I'm now very happy with the curve tracer's performance.

Picture
These are curves for a BC548. The tracer is in small signal mode and I have the scope's vertical channel 10X magnification on. Before moving the grounds to a single point, using the 10X magnification overwhelmed the display with noise making it unreadable. Now it's clean and easy to read.

Picture
The tracer completed. This should fit my needs nicely. I don't need to match or test transistors every day, but when the need arises this little curve tracer is likely all I'll need. It's no Tektronix unit but I can't really justify the cost of something like a Tektronix 575 for the amount of use it would get.

Page Created 2/29/2020
Last Edited 3/26/2020
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  • Home
    • About
    • Contact
  • Astrophotography
  • The Observatory
    • The New Observatory
    • - About the ExploraDome
    • - About the Lancaster Dome
    • - Building the Lancaster Dome
  • Equipment
    • CCD Cameras >
      • Orion Starshoot Pro
    • Mounts >
      • Orion HDX110 (EQ-8)
    • Telescopes >
      • Astro-Tech AT6RC
      • Celestron C-11 XLT
      • Zhumell 152mm Refractor
  • Projects
    • C11 XLT Mods
    • Orion SSPRO Camera >
      • Disassembled Views
      • Noise Reduction Mod
      • Temp Controller Mod
    • Ultima 8 Mods
    • Zhumell Refractor Mods
  • Non-Astronomy
    • Amateur Radio >
      • Boat Anchor Radios >
        • BC-348N Receiver
        • Collins 51J4 HF Receiver
        • R-392 HF Receiver
      • DIY >
        • Station Boom Microphone
      • Ameco >
        • Ameco AC-1
        • Ameco OCM
        • Ameco PT-2
        • Ameco R5A
      • Heathkit >
        • Heathkit SB-102 Station
      • Knight-Kit >
        • Knight Kit Span Master II
      • Yaesu FT-817 >
        • Yaesu FT-817ND
        • LDG Z-817 Autotuner
        • Windcamp LiPo Battery
    • Antique Radios >
      • Building A Radio Workbench
      • Radio Dial Neon Clock
      • Radios >
        • 1938 Zenith 6-S-254
        • Echophone EC-1
        • Eltz Radione 2
        • Panasonic RF-5000A
        • Silvertone Model 4465
    • Geiger Counters >
      • AN/PDR-27G Radiac Set
      • Lionel CD V-700 Geiger Counter
      • RCA WF-12A Geiger Counter
    • Test Equipment >
      • DIY Test Equipment >
        • DIY Curve Tracer
        • DIY Signature Tracer
      • Military Test Equipment >
        • BC-221-AF Frequency Meter
        • LM-21 Frequency Meter
        • TS-323/UR Frequency Meter
        • TS-465 C/U Sweep Generator
        • TS-505D/U VTVM
        • TV-3C/U Tube Tester
      • Tube Testers >
        • Alternating Current Sink
        • Drug Store Tester
        • EMC Model 200 Tube Tester
        • Hickok Model 6000A Tube Tester
        • Hickok OZ-1 (550X)
        • Precise Model 111 Tube Tester
        • Precision Model 10-12
        • Supreme Model 385
        • TV-3C/U Tube Tester
      • VTVMs and Multimeters >
        • B&K Model 290 Hi-Low FET Multimeter
        • Hickok 225K VTVM
        • McMurdo Silver VOMAX 900
        • Micronta 22-220 FET Multimeter
        • Simpson 360-2 Digital FET DMM
        • TS-505D/U VTVM
      • Hickok >
        • Hickok 19X RF Generator
        • Hickok 225K VTVM
        • Hickok 288X RF Generator
        • Hickok OZ-1 (550X)
        • Hickok 6000A Tube Tester
      • Simpson >
        • Simpson 360 DMM
        • Simpson 360-2 DMM
        • Simpson 480 Genescope
      • Supreme Instruments >
        • Supreme 385 Automatic
        • Supreme 560 Vedolyzer
        • Supreme 560A Vedolyzer
        • Supreme Model 561 AF/RF Generator
        • Supreme's Model 562 Audolyzer
        • Supreme Model 562 Audolyzer circa 1941
        • Supreme Model 562 Audolyzer circa 1946
        • Supreme Model 563 Audio Generator
        • Supreme Model 576 RF Generator
      • Other Test Equipment >
        • Rider 162 Chanalyst
        • Tektronix 326 O'scope
        • VU-Data Model 941B Oscilloscope
    • ---------------
    • Fossils
    • Rocks and Minerals
    • Star Trek >
      • Star Trek Rock Mood Lamp
      • Star Trek Communicator