This is a somehow easier to reproduce version of the Curve Tracer Project. It has the form-factor of an Arduino UNO (Leonardo), using very standard components. And yes, I saw that there are already similiar projects out there in the endless universe web, but they are all limited to 5V. What finally came out is a (THT) soldering exercise, a programming exercise and a course on transistor / amplifier components / circuits. Suiteable to fill one year of teaching electronics :-)

The shield houses all the components necessary for this project. A DC/DC converter built around a MC34063A generates a voltage of approx. 30 V. It is designed to deliver a current of max. 150 mA. Two 8/10/12 bit DAC's are used (together with a rail to rail opamp, AD822) to produce a voltage from 0 V to 27.0336 V. Whilst the Gate/Base drive is directly powered by the opamp, an additional transistor forms something like a "power stage" which shall handle currents up to approx. 100 mA. In order to increase reliability, we used a heatsink for it. The current is sensed by a 1Ω 1% resistor, amplified by a MCP6271 (48x) and finally read by the analog port of the UNO. The shield is capable to be controlled by a computer via the usb port. An external power supply 12 V / 1 A is necessary.

In order not to "forget" one type, we hacked together an overview. Some more commonly used types are measured in detail - to verify the functionality and correctness of this thing. The numbers in the field "connections" refer to the numbers on the shield.

#	?	TYPE	SYMBOL	CONNECTIONS	NOTE	DATASHEET
1		JFET N-CH		0: GND 1: DRAIN 2: GATE 3: SOURCE	V2 < V3	J309, J310
2		JFET P-CH		0: GND 1: DRAIN 2: GATE 3: SOURCE	V2 > V3	MMBF5460
3		MOSFET N-CH DEPLETION		0: GND 1: - 2: - 3: -	ID@UDS: + UGS: +/- RARELY USED	CPC3980
4		MOSFET P-CH DEPLETION		0: GND 1: DRAIN 2: GATE 3: SOURCE	ID@UDS: - UGS: +/- RARELY USED	CSD25483F4
5		MOSFET N-CH ENHANCEMENT		0: GND 1: SOURCE 2: GATE 3: DRAIN	ID@UDS: + UGS: + POWER AMPLIFIER	IRF7842
6		MOSFET P-CH ENHANCEMENT		0: GND 1: DRAIN 2: GATE 3: SOURCE	ID@UDS: - UGS: - POWER AMPLIFIER	IRF7240
7		BIPOLAR NPN		0: GND 1: EMITTER 2: BASE 3: COLLECTOR	Ibe > 0	BC849 BF199
8		BIPOLAR PNP		0: GND 1: COLLECTOR 2: BASE 3: EMITTER	Ibe < 0	BC859

The very first sketch. It is intended to test both DAC's. For setting this thing up and / or troubleshooting. You should see a sawtooth at port 2 and port 3. DC to approx. 27.034 V. The frequency is about 2 Hz. Do not load the outputs too much, there is no protection ...

This sketch ist suiteable to measure two-port devices such as zenerdiodes, diodes or resistors. Modify the sourcecode and then upload it. It will output columns of data which then may be copy / pasted into a csv file to be analysed with the spreadsheet of your choice. The power limitation is to protect the BC141 (0.8W) or BC140 (4W). In case it should reach a treshold, the sweep-loop will be aborted. ("break"). Below are some examples (excel). Scale is always y in [mA] and x in [V]. We averaged 64 values, but C5, C6 and C7 were not yet optimised at that time ...

This sketch ist suiteable to measure three-port devices such as npn transistors. Modify the sourcecode and then upload it. It will output columns of data which then may be copy / pasted into a csv file to be analysed with the spreadsheet of your choice. The base drive was 0 µA - 125 µA - 250 µA - 375 µA - 500 µA. The picture below shows a test fixture in action, suiteable for TO-39, TO-92, TO-5 and similiar sizes.

Max from Berlin designed a nice case for this shield. He even wants to share his work with you. Download the zip file below his picture ...

Daniel spent quite some time to build this board and came up with some suggestions on how to improve this shield. The version 2.2 is made possible by his extensive feedback. Even more, he allowed to publish his developped c-code here. The main improvement suggested to add a Resistor of 4.3 kΩ at the output of the step-up converter to improve stability, but we can get away with a change of component values. New is the value of R7 = 3 kΩ and R6 = 120 Ω. This shall have a similiar effect as adding a resistor of 4.3 kΩ.

Using a USB galvanic isolator is strongly recommended.

The webmaster does not read these comments regularely. Urgent questions should be send via email. Ads or links to completely uncorrelated things will be removed.