Electronics
Tips and Tricks
See the rest of the Daycounter
Lab Book.
This is a list of useful
electronics engineering tips and tricks. Guaranteed
One Percent Resistors
1% resistors are often required in
electronics applications, however, during manufacturing, sometimes
manufactures will make a mistake by ordering a generic resistor that may
be 5% or even 10% in order to save costs. A useful trick is to
specify resistors that only come in 1% values. For example if you
have a resistor divider that requires a ratio of 10, rather than using a
10K ohm resistor and a 100K ohm resistor, specify a 10.2K and a 102K
ohm instead. This way there is no possible way to use higher tolerance
resistors.
Minimizing Forward Voltage Drop Across
Diodes
Diodes are often used to prevent reverse
polarity of power input leads. In battery powered applications this
can present a problem, because diodes have a natural voltage drop, that
lowers the available supply voltage to the circuit. For example, if
you have a 6V battery which powers a 5V circuit, then there isn't much
margin. A simple trick to lower the forward voltage drop is to place
diodes in parallel. For example, the BAT54 is a dual diode that
comes in a SOT23 package. A single diode has the following voltage
drop characteristics:
| If (mA) |
Vf (mV) |
| .1 |
240 |
| 1 |
320 |
| 10 |
400 |
| 30 |
500 |
| 100 |
800 |
In the case where our circuit draws 150mA,
then if we use three BAT54 diodes in parallel, then the forward
voltage drop goes from 1V to less than 500mV, since 6 diodes divide the
current down to 25mA.
Manufacturer Links
The best way to find electronic parts is to use our
free Electronics
Component Directory, where a myriad of electronics manufactures are
listed.
Other Electronics Links
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articles and tutorials.
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