Question

what is the voltage across load resistance
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Answer 1

Answer:

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Explanation:

Each anode load resistor dissipates 0.3 W, which is easily catered for by the 25 W wirewound type specified for the input cascode, but (considering the second stage) is more than can be safely dissipated by a 0.6 W MRS25 resistor randomly positioned on a PCB. Noise at the second stage is not an issue because ra is low enough to shunt resistor noise and signal levels are much higher, so 2 W metal film resistors were perfectly adequate, although matching remains worthwhile, so ±1% types would be preferable if only they could be found (±2% used to be available).

At the other end of the resistor performance spectrum, the source followers need gate-stopper resistors, and as there is no gate current, there can be no voltage drop across these resistors to cause excess noise. Thus, we cheerfully choose carbon film resistors because the increased resistivity of the carbon matrix compared to the nichrome alloys permits reduced inductance and less likelihood of source follower radio frequency oscillation.

The second differential pair needs grid-stopper resistors, and past experience with E88CC has shown that surface-mount types close to the valve pins are the most effective. As mentioned earlier, surface-mount resistors are generally thick film and suffer excess noise, but the same argument applies to the valve as the FET: if there is no grid current there can be no voltage drop and no excess noise.

Having chosen our components, we know how large they are and we can plan our PCB layout.

Electrical Power Generation and Control Options for Wind Turbines

S. Gair, in Energy for Rural and Island Communities: Proceedings of the Second International Conference, Held at Inverness, Scotland, 1–4 September 1981, 1982

LOAD CONTROL

Schemes employing switched load resistors enable a stepwise load approximation to be made to the powered ∝ (rotational speed)3 characteristic of the wind turbine. Operation within the maximum current loading of the generator can be set and the discrete resistance values selected so that for a particular wind speed, operation of the turbine is held fairly close to the Cp maximum value. This method of control is ideally suited to small stand alone wind turbines and has the merits of being cheap, simple and effective where the load demand is for resistance heating.