Kevin Weddle

Thank you audioguru. Although Schmitt triggered digital devices seem more reliable, isn't it a form of positive feedback that prevents noise from switching the device?

Does a varactor diode release any stored energy when the voltge is removed, like a capacitor or inductor does?

A circuit based on a 1KHz clock has a longer pulse transistion time than a 10Khz clock. But couldn't it have the same transistion time? Is there a circuit to reduce pulse transistion time and make a low frequency digital circuit perform better?

For example, a passband amplifer can have as little as 20db/decade roll-off. A cascaded passband amplifier can have a much higher roll-off. I normally see many filters in a circuit, is it to achieve an exact amount of filtering? I have 120Hz 10mVpp ripple coming from my 7805 voltage regulator, should I filter it out?

LC filters have good attenuation at low frequencies and are less suitable at higher frequencies. 40db/decade is the attenution. Is -3db the nominal attenuation for unwanted frequencies? Should the final attenuation be more or less than -3db in order to be finished with filtering.

Can a parallel LC, buffered from an oscillator, be used to determine the frequency of an oscillator? A parallel LC has only one resonant frequency.

A typical MOSFET can have a VGS of 3 volts. A bipolar transistor has a base emitter bias of about .7 volts. The emitter voltage is often low with both transistors, so a 5 volt voltage source would have less than 2 volts to bias a MOSFET.

How can MOSFET's be used in low voltage circuits when their VGS is high?

There are several ways to calculate light bulbs. Producing a 60W light bulb at 120Vac is one way. Measuring the resistance of the filament and the applied voltage is another way. But, the best way of all, is to determine the combined resistance and reactance, then apply the voltage and then determine resistance.

What diode does it take? Is it .7V or or less than that to turn a circuit off.

Inductors can self resonate because of their interelctrode capacitance. Neutralization is an attempt to neutralize interelectode capacitance with an inductor. Typical of higher frequency circuits. But their performance is bad due to poor engineering and poor production. Almost they don't work but minimal.

Some transistors have a collector to base capacitor, but no inductor. Does that mean a single capacitor is acceptable and that sometimes neutralization is better? Would it depend on the frequency?

A single piece of wire can have a very low resistance, but 200 to 300 amp requires a higher voltage.

Just connect a 12V battery to the input power connector. To be sure, use an oscilloscope to verify that the adaptor connected to the camera produces 12V regulated. If it's 12V regulated, then try a higher capacity battery.

I think you can substitute a transformer and rectifier for capacitors and diodes if the power requirements are not high. But it would require many large capacitors and isn't worth the trouble. Generally you would require a transformer, rectifier, and voltage regulator.

Okay, I understand the stability with that biasing. Does that mean that there is little versatility with a 2N3904? Signal amplifiers require several stages of varying amplitudes and load impedances. Do you recommend different transistors all operated at their data sheet typical values?

Replacing an AC adaptor with just a series of small batteries is probably not good enough. A larger capacitor battery is what you could try.

A voltage divider bias at 10 times the current creates a low impedance for the signal source. An emitter resistor 1/10 the collector resistor is only a gain of 10. A single pole RC will reduce the critical frequency %70.7 and the bandwidth small. But given the inherent voltage changes in a circuit, isn't 1mA too close to cutoff and the beta at that current isn't linear, but becomes linear at higher currents?

What is the lowest current a 200mA transistor should be operated at to prevent distortion caused by bias drift?

The signal can be converted to a clock signal with an opamp. A counter will set the last bit after a number of clock pulses. This bit can be used to power an LED, which will flash. An analog voltmeter or digital voltmeter can measure AC up to a maximum frequency and amplitude across a capacitor. But it would not be very accurate.

The easiest way to generate -50V is from a battery. The PIC output can switch a MOSFET that is in series with the battery and the load. The positive terminal of the battery is connected to ground and the negative terminal is connected to the load.

You can't re-engineer an electronics product to be safer in most circumstances. Old pieces of equipment get worn and can become more of a danger.

You can guess as to an approximate frequency range using other measurement devices. But an oscilloscope or other frequency measuring device is required at higher frequencies and lower amplitudes.

A transformer will deliver a high enough voltage that you want. High voltage transformers are expensive, but can usually be found in electronics products no longer used, and be cascaded for high voltgage. Be aware that high voltage burns and shock can occur, and a high enough voltage can lay you in the hospital.

Two N channel MOSFET's can replace the two IGBT's in your circuit. An H bridge is used to produce a polarity change across a load. If your circuit is an H bridge, then the load is what makes it an H bridge. It looks like the voltage at the output is fixed by the zener diode, from your schematic.