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Type: Posts; User: wwfeldman

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1. ## Thread: Introductory literature on PLD

by wwfeldman
Replies
4
Views
51

### Closed: Re: Introductory literature on PLD

good start
go through the examples

when you run into a problem,
show the work you did, what the computer told you,
and...
2. ## Thread: Converting drill file in um to mm

by wwfeldman
Replies
3
Views
91

### Closed: Re: Converting drill file in um to mm

i think you did good

my apologies about the metric system lesson

by wwfeldman
Replies
1
Views
55

### Closed: Re: Interdigitated capacitors

same as any other capacitor
basic model two plates, area A, charge q, separation d, dielectric k, etc

then there's another one in series
and another in series etc
...
4. ## Thread: Converting drill file in um to mm

by wwfeldman
Replies
3
Views
91

### Closed: Re: Converting drill file in um to mm

mm is millimeter, 10^-3 m
um is micrometer, 10^-6 m

converting requires moving decimal point 3 places corresponding to multiplying or dividing by 1000,
depending one which way you're going.
...
5. ## Thread: Stacking diodes for high voltage rectification

by wwfeldman
Replies
18
Views
314

### Closed: Re: Stacking diodes for high voltage rectification

100 uf4007 plus 100 R & C for snubber plus 100 voltage sharing resistor
vs
10 K50UF plus 10 R & C for snubber plus 10 voltage sharing resistors

now compare board space, parts cost, inventory...
6. ## Thread: Will I be able to drive LED with attached analog circuit ?

by wwfeldman
Replies
3
Views
150

### Closed: Re: Will I be able to drive LED with attached analog circuit ?

i think it will work
but the LED is always on, and there are simpler circuits to just turn on the the LED
at 3.5 mA the LED will not be very bright.
7. ## Thread: Stacking diodes for high voltage rectification

by wwfeldman
Replies
18
Views
314

### Closed: Re: stacking diodes for high voltage rectification

Bridge Rectifier won't Rectify

you would need some way to guarantee that all of the diodes carried their share of the voltage

since the uf4007 is rated at 1000 V, 100 of them...
8. ## Thread: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

by wwfeldman
Replies
2
Views
270

### Closed: Re: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

An attempt:

as you know:
consider the bohr model of hydrogen:
an electron can orbit the nucleus only in specific quantum levels
the lowest level, n = 1, is at -13.6 eV
the next level, n = 2,...
9. ## Thread: damaged remote control

by wwfeldman
Replies
4
Views
173

### Closed: Re: damaged remote control

treat it like a wet cell phone

put it into a container with rice all around for a day or 2 to dry it out
get all of the rice dust off it
then put it back together with a fresh battery.
10. ## Thread: Single conductor inside hollow conductor

by wwfeldman
Replies
25
Views
879

### Closed: Re: Single conductor inside hollow conductor

if anyone wishes to continue he discussion of potential, emf and voltage, etc,
as this seems somewhat far afield from kajunbee's question
11. ## Thread: Single conductor inside hollow conductor

by wwfeldman
Replies
25
Views
879

### Closed: Re: Single conductor inside hollow conductor

@easy peasy
emf and potential are both measured in volts
when the "voltage" is caused by charges, it is potential and the potential difference between two locations is the voltage we measure
when...
12. ## Thread: Whats the best way to ESD damage a PCB

by wwfeldman
Replies
6
Views
312

### Closed: Re: Whats the best way to ESD damage a PCB

it also depends on the humidity in the air
this time of year, north america, europe etc have relatively high humidity and
static charge does not build up

if you did the carpet shuffle, or the...
13. ## Thread: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transformer

by wwfeldman
Replies
17
Views
739

### Closed: Re: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transform

this test is accomplished by tieing all of the primary leads together and all of the secondary(ies) leads together
and then applying 3750 VAC

3 mA seems like a lot of leakage
14. ## Thread: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transformer

by wwfeldman
Replies
17
Views
739

### Closed: Re: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transform

the transformer tested for a longer time is likely built better

i expect more critical application require a longer isolation test

15. ## Thread: Nominal current of diode bridge rectifier

by wwfeldman
Replies
5
Views
271

### Closed: Re: Nominal current of diode bridge rectifier

the data sheet says rectangular pulses, 1/3 of the time, as noted above, 90A output current

conduction by any one diode 1/3 of the time is the most one would expect from a 3 phase sine wave input...
16. ## Thread: 12 vdc led running very hot

by wwfeldman
Replies
12
Views
378

### [SOLVED]Closed: Re: 12 vdc led running very hot

please provide the circuit the LEDs are in, the part number of the LED
and any known voltages or currents
17. ## Thread: Isolate R37 from Equation

by wwfeldman
Replies
2
Views
185

### Closed: Re: Isolate R37 from Equation

try this:
apply voltage divider at the + input of the op amp V+ = ...

assuming a perfect op amp, V- and output = V+

combine R25 and R28 to one equivalent resistor

assuming Vo is open,...
18. ## Thread: Drive motor through IRF520 MOSFET module and Arduino

by wwfeldman
Replies
1
Views
124

### Closed: Re: Drive motor through IRF520 MOSFET module and Arduino

please draw the circuit for the arduino, the MOSFET Drive Module and the motor
show the connections between the arduino the mosfet driver and from the mosfet driver to the motor
show all voltage...
19. ## Thread: How to use the same RELAY on 12V & 24V vehicles

by wwfeldman
Replies
10
Views
368

### Closed: Re: How to use the same RELAY on 12V & 24V vehicles

what load does the relay handle? V? I? etc

Kyotto makes a series of solid state relays with a control voltage range of 4 to 32 V

load voltage ranges 24 to 280 VAC and currents 10, 15, 25, 40,...
20. ## Thread: Single conductor inside hollow conductor

by wwfeldman
Replies
25
Views
879

### Closed: Re: Single conductor inside hollow conductor

@easy peasy:
potential (voltage) is the energy per unit charge based on static charge distributions
things where we use V = sum of kq/r or integral thereof for continuous charge distributions
...
21. ## Thread: HP 54520A Blown Fuse Problem

by wwfeldman
Replies
28
Views
1,105

### Closed: Re: HP 54520A Blown Fuse Problem

suggestion:
find an identical 'scope on ebay or a used equipment place
get it for spare parts
if it turns on, but the 'scope doesn't work, you have a new power stage

useless suggestion:
when...
22. ## Thread: Single conductor inside hollow conductor

by wwfeldman
Replies
25
Views
879

### Closed: Re: Single conductor inside hollow conductor

the outer conductor of coax is usually stranded and woven
if it was solid, like a pipe, it wouldn't bend.

when i asked where the return path was, i did assume a current
as you know, there is...
23. ## Thread: Single conductor inside hollow conductor

by wwfeldman
Replies
25
Views
879

### Closed: Re: Single conductor inside hollow conductor

yes
where is the return path of the AC current?
24. ## Thread: OP07 circuit output voltage?

by wwfeldman
Replies
24
Views
735

### Closed: Re: OP07 circuit output voltage?

this question appeared in this thread
13.9 V instead of 2.75 v, Which parts are failing?

so my question is what are umsch1 and umsch2 connected to?
umsch1 is directly connected to the...
25. ## Thread: What dc can u measure?

by wwfeldman
Replies
5
Views
422

### Closed: Re: What dc can u measure?

assuming sinusoidal waves, and since there is no apparent load, all three circuits act as peak detectors.

If Veff is Vrms, then Vpeak = sqrt(2) * Veff or Vpeak = sqrt(2) * 20,5 V = 28.99 V
...
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