A homebrew Curve Tracer with insignificant BOM but surprising skills !
A Curve Tracer is a Device which will show the Voltage / Current dependency
of an electronic part. It is therefore suiteable to discover characteristics of
electronic parts - and to quickly check if they are o.k. - or if the smoke left aleady.
This Project is useful for educational reasons, as it is simple but clever.
Fig.1 .:. Homebrew Curve Tracer - a very handy Tool !
All we need is an Oscilloscope with an x and an y input.
(This feature is available in almost every Oscilloscope.)
The horizontal axis represents the Voltage (x) whilst the
vertical axis (y) represents the Current.
Fig.2 .:. Schematics
The minimum Configuration uses only three parts :
• A Transformer
• A Current Limit Resistor (R1)
• A Current Sense Resistor (R2)
(There is a 330pF Capacitor to reduce noise, parallel R2)
We used a Transformer with 15V which will deliver 30Vp or 60Vpp. In order to
limit the current to 10mA, R1 was chosen to be 3kΩ. R2 was chosen to be 10Ω.
A more luxurious Version may use a Switch to select different maximum Currents.
Fig.3 .:. Built 'on the fly'
With this configuration, the following curves have been measured :
(Set the Y-Channel to 'inverting')
Fig.4 .:. No D.U.T. - High-Z
Fig.5 .:. A Resistor of 2.5 kΩ - 5V/Div : 2mA/Div
Fig.6 .:. 1N4007 Diode
Fig.7 .:. A Zener Diode of 18 V
Fig.8 .:. A Zener Diode of 9.1 V - the other way
Fig.9 .:. Two Diodes 1N4007 - antiparallel
Fig.10 .:. Two Diodes 1N5711 (Schottky) - antiparallel
Fig.11 .:. Two Diodes 5082-2835 (Schottky) - antiparallel
Fig.12 .:. A Capacitor - C = 1 µF
Fig.13 .:. A Resistor 2.5 kΩ in series with a Capacitor C = 1 µF
Fig.14 .:. A Varistor, EPCOS S05K25
Curve Tracer Project .:. Part 2
This Section will add Gate / Base Drive in order to examine Transistors.
Click here to go to the advanced Curve Tracer Website.
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