What should the amplitude of the square wave be to achieve s

What should the amplitude of the square wave be to achieve switching?

Calculate and measure the voltages at points A and B.

What is a relay and how does it work?

What is the purpose of the diode D1 in this circuit?

What happens when you increase the frequency?

Where do you think the problem originates from and why?

Solution

1. I need to transform a bipolar sine wave (varies from -5 V to 5 V, 1 kHz) to a square wave for further digital processing (0 to 3.3 V).

The important thing is that this sine wave can\'t be distorted, so there can\'t be any limiting diodes at the input.

I have got only 3.3 V and 5 V voltage supplies. An obvious way to go is an op-amp working as a Schmitt trigger, but it can handle -5 V at the input with a single positive 3.3 V supply.

2. Let v > 0.7 V and diode is forward biased. Applying Kirchoff’s voltage law
10 ix1k v = 0
10 - [{v-0.7}/500] (1000) - v = 0

10 - (v-0.7) x 2 = 0

v = 11.4/3 = 3.8 V

3. A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. The heart of a relay is an electromagnet (a coil of wire that becomes a temporary magnet when electricity flows through it). You can think of a relay as a kind of electric lever: switch it on with a tiny current and it switches on (\"leverages\") another appliance using a much bigger current. Why is that useful? As the name suggests, many sensors are incredibly sensitivepieces of electronic equipment and produce only small electric currents. But often we need them to drive bigger pieces of apparatus that use bigger currents. Relays bridge the gap, making it possible for small currents to activate larger ones. That means relays can work either as switches (turning things on and off) or as amplifiers (converting small currents into larger ones).

4. Since an inductor (the relay coil) cannot change it\'s current instantly, the flybackdiode provides a path for the current when the coil is switched off. Otherwise, a voltage spike will occur causing arcing on switch contacts or possibly destroying switching transistors

5. Wave velocity, also known as water waves, is considered constant. Wavelength andfrequency are inversely proportional; increasing the frequency decreases the wavelength.

6. This square wave generator is like the Schmitt trigger circuit in that the reference voltage and is a difficult device to get a good square wave out of. This is caused by it\'s poor high frequency response. You can built a relaxation oscillator much easier with a 555 oscillator/timer chip. A 7555 is a 5V Cmos version that might work as well and they are sold at Radio Shack