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Results tagged with diodes
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user 90588
Diodes are semiconductor components made from a P-type (or metal in Schottky diodes) and N-type material (usually silicon, but germanium, selenium, and gallium arsenide can also be used), that allow current to flow in one direction only.
0
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Resistance of a diode
The dynamic resistance does dissipate heat, as does the current flowing through the 'fixed' V in series with it.
Imagine a diode with 1 mA, and 0.726 V. this is 726 uW total power. The small signal d …
1
vote
Industrial construction of pn-junction diodes?
Separately processed pieces of semiconductor mechanically joined won't work well as a pn junction because the facing surfaces need to be perfectly joined (as the crystalline structure level), and with …
2
votes
Accepted
Why don't the minority carriers combine with the majority carriers in a PN junction?
The minority carriers in a semiconductor are not from manufacturing defects, but from spontaneous generation. Basically, in a semiconductor, electron-hold pairs are continuously being generated (using …
6
votes
Accepted
Electron Flow Confusion
Electrons can't flow in that direction (right to left) though a diode.
Yes, a small transient current flows while the voltage builds up across the diode (it acts like a small capacitor). In practice …
3
votes
Accepted
Low loss method of connecting two dissimilar battery voltages together without a diode?
You need an 'Ideal Diode Controller'. Basically this is a comparator (comparing the V across a FET (which is acting as a switch), and turning on the FET if necessary.
Sometimes these are slow, so a pu …
3
votes
difference between reverse saturation and leakage current
Zener breakdown typical occurs for very highly doped diodes with a BV less than about 5V; some diodes have 'zener' voltages of only 3 V. … These are called backwards diodes, or tunnel diodes. …
1
vote
Diode Forward Bias behavior?
Actually there are some diodes that breakdown in forward bias -- these are called Esaki diodes or tunnel diodes. … These diodes are not used very much any more, but used to be used in microwave amplifiers and radars before transistor performance was good enough. …
1
vote
Bridge rectifier & minimum diode voltage
The representations are simplified. In reality there is a gap (0 V out) when the input is between -0.7 and +0.7 V.
The peaks of the output are also 1.4 V lower than the input peaks.
The R & C filter p …
3
votes
Net current when applying an electric field to a PN junction
In the 1st equation, the 1st term is drift (current driven by electric field) across the junction, the 2nd term is diffusion (current driven by concentration gradients) across the junction in the oppo …
13
votes
For a lower voltage drop one could use Schottky diodes, but what are the disadvantages of Sc...
For essentially the same reason that schottkys have low forward drop, they have large reverse currents.
From the diode equation:
\$I_f = I_s\cdot e^{\frac{-qV_f}{kT}},
V_f = \frac{kT} {q}\cdot \ln …
1
vote
Accepted
Bench supply protection diode replacement
It's there to protect against 'accidents' like you had. It also is useful if 2 power supplies are connected in series and the combination is shorted. This also prevents the output electrolytic from be …
3
votes
Determining which diode I need
Most common diodes like that are 1N914, or 1N4148. A 1N4001 (or 4002, 4003.. 4007) would probably also work.
How did it fail ? How do you know it is failed ? …
2
votes
Accepted
Does the N material need to be directly touching the P material?
Depending on their construction, the wire-p-wire or wire-n-wire portions may or may not act as just resistors, or as schottky diodes. …
0
votes
Accepted
MAX5035 Buck Converter Internal Body Diode
The VF of the diode is perhaps not so strictly required; a well-designed IC should not have strict requirements on this parameter (it should not have large uncontrolled diodes on the LX node). …
1
vote
"Sharp" transistor switching / minimizing fading effect
If you do want stay with the BJR circuit, then you can get a sharper transition by:
Add a R across the B-E of Q1 -- use 500 Ω (470 is available) . Now even small leakage in the zener won't directly t …