When developing electronics, it can be useful to have a way to draw or measure a specific current. While professional digital loads are quite expensive, a high-wattage resistor is sufficient in many cases. To have a small ( 16,5 x 10 cm), universally usable resistive load, I ordered a selection of resistors that allow me to draw commonly used currents like e.g. 50mA, 100mA, 200mA, 0.5A, 1A… for the common voltages of 3.3V, 5V or 12V. Additionally I included 0,1 Ohm resistors as shunts for measuring the current. To facilitate the combination of the used resistors to the desired total resistance, I placed the terminals at 19mm to use existing lab-socket jumpers and decided to connect the left & right resitor permanently. While this has the drawback of not allowing concurrent use for 2 outputs at the same time, it reduces the amount of required cables as well as plug/socket and cable resistances and inductances.

Costs ~ 55 €
Time ~ 3 h (excl. planning 😉 )
Materials used:
– 2x resistors WD25 (25W) 0,1 Ohm [5 €]
– 2x resistors WD25 (25W) 1 Ohm [4 €]
– 2x resistors WD25 (25W) 3,3 Ohm [4 €]
– 4x resistors WD25 (25W) 10 Ohm [7 €]
– 4x resistors WD25 (25W) 100 Ohm [7 €]
– 1x aluminium heatspreader 160 x 100 x 40 mm [ 15 € ]
– 2x aluminium stripe (320 x 10 x 2mm, bent with 90° angles as 10-70-160-70-10 ) [1,5 €]
– 1x aluminium stripe (250 x 10 x 2mm, bent with 90° angles as 45-160-45 ) [0,5 €]
– shrinking tube for isolation of the ‘feet’ [0.5 €]
– 40x short self-cutting screws (e.g. 9,5 x 3 mm) [2 €]
– 21x colored 4 mm lab-plug terminals [4€]
– solder-wire & desolder-wire (or some fine copper-mesh / wire)
– thermally conductive adhesive tape (double sided) [4 €]

Tools:
– drilling machine (preferably with a stand for 90° angles)
– soldering iron
– scalpel / cutter / scissors for the tape
– Isopropanol as drilling lubricant
– 2.5 / 8 mm drills (preferably sharply cut, cobalt coated drills)