Velleman K8000 - DAC High Power Amplifier - Measurements
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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.
| 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 |
| 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 |
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 | 0 | 0 | 0 |
| 1 | 0 | 0 | 0 |
| 2 | 0.2 | 0.29 | 0.21 |
| 3 | 0.72 | 1.21 | 0.77 |
| 4 | 1.25 | 2.12 | 1.47 |
| 5 | 1.4 | 3 | 2.27 |
| 6 | 1.64 | 4.04 | 3.02 |
| 7 | 1.8 | 4.95 | 3.9 |
| 8 | 2 | 6.26 | 4.93 |
| 9 | 2.16 | 7.35 | 5.59 |
| 10 | 2.25 | 8.13 | 6.35 |
Copyright ©1998-2022 Vanderhaegen Bart - last modified: August 24, 2013
