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Velleman K8000 - DAC High Power Amplifier - Measurements

Measurements

On this page you can find the results of some measurements I did on the circuit. Some explainings: Ucontrol is the control signal from the K8000. Ubrigde is the output signal from the voltage regulator, before it is passed to the polarity reverser.

Measurement 1: Control voltage vs brige voltage with load (electric drill)

Ucontrol (V)Ubridge (V)Iout (A)
0 0 0
1 0 0
2 0.37 0.11
3 1.41 0.48
4 2.24 0.69
5 3.23 0.83
6 4.14 0.93
7 5.09 1.01
8 6.15 1.07
9 7.08 1.14
10 8.1 1.2

Measurement 2: Control voltage vs brige voltage with load (electric drill + halogene lamp)

Ucontrol (V)Ubrigde (V)Iout (A)
0 0 0
1 0 0
2 0.29 0.2
3 1.21 0.72
4 2.12 1.25
5 3 1.4
6 4.04 1.64
7 4.95 1.8
8 6.26 2
9 7.35 2.16
10 8.13 2.25

Measurement 3: Control voltage vs output voltage (electric drill + halogene lamp)

These measurements are maybe the most important ones. It shows the voltage drop caused by the FETs: the higher the load (current) the higher the voltage drop gets.

The constatated drop corresponds with the excepted drop. For example: a control voltage of 10 VDC causes a voltage of 8.13 V at the input of the brigde. There is a current of 2.25 A and the effective output voltage is 6.35 V. This means there is a voltage drop of 1.78 V over the two conducting FETs, or 0.89 V over each single FET. Using ohmse law we can calculate a resistance (Rds) of 0.4 Ohm, which was to be expected.

Ucontrol (V)Iout (A)Ubridge (V)Uout (V)
0 00 0
1 00 0
2 0.20.29 0.21
3 0.721.21 0.77
4 1.252.12 1.47
5 1.43 2.27
6 1.644.04 3.02
7 1.84.95 3.9
8 26.26 4.93
9 2.167.35 5.59
10 2.258.13 6.35

Copyright ©1998-2017 Vanderhaegen Bart - last modified: August 24, 2013