# Tagged Questions

71 views

### Determine material of Zener's diode based on its characteristics

I have a plot log (I) = f(U) for a few diodes: Silicon diode, Germanium diode, some LED and a Zener diode. I need to determine the material, from which the Zener diode is made based on the positioning ...
194 views

### What's the relationship between volts and amperes in batteries?

I recently bought a bag of 100 5mw 4.5V laser diodes (the spec said they have "driver: out"). My idea was to connect two and two of these in series to get something that needs 9V, and then connect ...
252 views

### Zener diode can vary current flow to maintain voltage drop, how does this magic effect work?

So it seems that a zener diode is "magically" able to change its resistance to allow more current to pass through it, such that the voltage drop across the diode remains the same. My question is ...
170 views

### How to reduce voltage from a battery to a motor [closed]

I have a 14.8v battery and I want to run a motor on 13v. What is the best solution to reduce the voltage from 14.8v to 13v?
240 views

### Step-down transformer AC to DC voltage conversion problem?

I got a step down transformer from an old black and white CRT TV that is about 18v 0 18v, 10A AC current output. I wanted to convert AC to DC, so used four 1N4007 diodes as a bridge rectifier. When I ...
248 views

### Vin output voltage of an Arduino

I have got a very simple and fast question. I have connected 6v to the power jack of my arduino, and when I tested the output voltage from the Vin, it turns to be 5.3v with no connection and 4.8 with ...
357 views

### Voltage drop assumption on diodes (LEDs, etc.)

I've always wondered why is it valid to assume some voltage drop (different from the junction voltage drop) on diodes or LEDs from the power up of a circuit. It simplifies the analysis, but it's ...
162 views

### Can I use more diodes for lower voltage drop and higher current?

The problem is simple: I have bought an UBEC, which should accept 7,6V from my battery and give me 5V to power my electronics. But the one I bought does not give me 5V, but 5.3V - that could cause ...
93 views

### Doping concentration in anode region

I'm stuck with this doping problem and can't figure out where to go with it. The built-in voltage of a GaAs pn junction diode is 1.25 V when the diode's temperature is T = 320K. The cathode ...
300 views

### Compensating the forward voltage drop of a diode signal rectifier

I am reading Arts of Electronics and they are showing this circuit: It says that D1 compensates for D2's forward drop by providing 0.6V of bias. I don't understand this circuit at all. Is the +5V ...
220 views

### Voltage doubler or not?

I got a quick question! Is the circuit depicted in the link indeed a voltage doubler or is it just a bridge rectifier with smoothing capacitors?
1k views

### Why do diodes have a voltage drop?

Is resistance what makes a diode have a voltage drop? Or is it impedence? If it is electrical energy being converted to light, please tell me what this effect is called.
216 views

### Can I use more diodes to reduce the voltage off a diode bridge?

I have a transformer labeled as providing 9Vac, 3.36 A. It appears to provide 9.4 v ac according to my multimeter. It runs through a diode bridge (WAB 040 diodes -- already fried the last version), ...
224 views

### Dropping voltage for red channel on RGB LED

I'm looking at a Multicomp OSW-8349 RGB LED, which has a Vf of 3V min / 4V max for the green and blue channels, and a Vf of 1.8V min to 2.8V max for the red channel, at 350mA. I'm planning on ...
104 views

### Scaling voltage to meet two conditions at once

I am using an IC (STM6600) which, among other functions that I need, is also capable of Undervoltage Monitoring. It works like this: The IC monitors VCC in comparison to two thresholds, V_Low and ...
149 views

### Setting a part's VCC slightly lower than board's supply voltage

I'm interested in using the undervoltage detection feature (in addition to the primary function) of this chip. This IC draws 6 uA (microamps), and accepts any VCC between 1.6V and 5.5V. The ...
1k views

### Why is the voltage across a reverse biased diode equal to source voltage?

Why is it not equal to zero since a reverse biases diode is essentially an open circuit?
132 views

I have the following circuit I am having some trouble determining the relationships between Iac, Io and Iacpk. I'm not quite seeing how the final equation for Iac was determined, specifically ...
203 views

### diode nightmares

Let me start by saying I am a complete amateur trying to stumble my way through some pretty basic PCB design, and I have run into a problem selecting diodes. The PCB I am designing will be for some ...
1k views

### Simple pn junction / diode question

Lest assume we have the setup presented in the image. What would be the potential difference (not voltage drop) between points A and B? Why? What effect will the pn junction barrier potential have ...
916 views

### How does the Villard circuit double voltage?

How does the Villard circuit double voltage? I don't understand the capacitor role when the voltage sinewave goes negative.