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Type: Posts; User: schmitt trigger
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3rd December 2019, 15:19
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- 350
Closed: Re: In accuracy in AC Voltage measurement
The semiconductor companies sell double diodes which are specifically designed to protect microcontroller inputs from an overdrive.
These have low leakage and low Vf.
Having said that, if your... -
3rd December 2019, 04:08
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- 3
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Closed: Re: Iran Core Transformator No Load Current (Core material)
You need to measure real core loss, with a wattmeter that measures true power= V*I*cos(alpha).
The core material with the lowest losses, all other things kept identical, is the best.
When I... -
27th November 2019, 17:03
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Closed: Re: Opamp buffer with 400nF output capacitance going unstable?
Regardless of what compensation scheme you choose, hopefully you have (or can borrow) a "Bode Box" to check the phase/gain margin.
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25th November 2019, 15:45
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Closed: Re: Regarding UC3844 IC used for PWM switching
It appears that the schematic either:
- has a drawing error
- they are operating the 3844, which is a current mode controller, in voltage mode.
Incorrect in either case.
EDIT: Indeed, you... -
22nd November 2019, 15:28
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Closed: Re: High Input Current DC-DC Converter?
The only way to properly decide, is to delve into app notes and data sheets from major semiconductor manufacturers.
Lots of reading, my friend.
When you find something similar to what you are... -
22nd November 2019, 15:19
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[SOLVED]Closed: Re: ACS712-5A AC Current Reading - How to?
Something that you have not mentioned is the load type.
All practical loads will have some sort of inrush current behavior.
Some may last a couple of cycles, like the capacitor charging in... -
19th November 2019, 17:20
Thread: Functionl Generator 600 MHz
by schmitt trigger- Replies
- 7
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- 438
Closed: Re: Functionl Generator 600 MHz
Function generator, like a sine, wave, triangle wave generator?
At 600 Mhz, you either have pure sine waves or a trapezoidal waveform.
Because of the large amount of harmonics present in a... -
19th November 2019, 16:13
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Closed: Re: Switch +/- 15v supply for audio preamp
50 mA across 100 ohms would yield a voltage drop of 5 volts. Worse, the power dissipation, with all the channels enabled, would be 2 watts. I haven't seen the device ratings, but unless it is an IC...
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19th November 2019, 02:15
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Closed: Four band audio bargraph display, using IN-13 Nixie linear bars.
A couple of years ago, I stumbled upon an IN-9 Nixie linear display datasheet in Russian.
Some fellow members (Prairedog and Altaero) in this forum, helped me translate it and my curiosity was... -
18th November 2019, 15:00
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- 4
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Closed: Re: Transformer Phase shift used in isolated zero crossing detectors
Indeed, for applications which are not critical, this slight error could be calibrated via software to a much smaller error.
I made another experiment, although I did not take waveforms:
This is... -
17th November 2019, 23:00
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- 4
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Closed: Transformer Phase shift used in isolated zero crossing detectors
In this and other forums, the question arises whether the same low power transformer used in the power supply, can be used to obtain an isolated sample for a zero crossing detector.
I remember... -
11th November 2019, 21:35
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Closed: Re: Motor dummy load resistor calculator
What type of motor is the motor which is electrically loaded?
Is it a BLDC or separately excited synchronous motor?
If it is an induction motor, it will not self generate back EMF. -
11th November 2019, 01:50
Thread: reason for 50 Hz ac current
by schmitt trigger- Replies
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- 548
Closed: Re: reason for 50 Hz ac current
The main reason for commercial power 50/60 Hz was chosen and not a lower frequency is twofold:
-Lamp flicker and radio hum. Lower frequency ripple requires larger filter components.
-The... -
7th November 2019, 17:54
Thread: 2SC1971 Amplifier problem
by schmitt trigger- Replies
- 12
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- 608
Closed: Re: 2SC1971 Amplifier problem
Can you attach those datasheet files?
I'm not saying it is not possible, but I've never, ever seen a TO220 transistor whose tab wasn't the collector.
The reason is very simple: heat transfer is... -
7th November 2019, 17:48
Thread: Is it a transistor or a mosfet?
by schmitt trigger- Replies
- 17
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Closed: Re: Is it a transistor or a mosfet?
Hope that you have a DMM
Start with the information on the following page:
https://engineeringtutorial.com/testing-a-transistor-with-a-digital-multimeter/
There are other web pages showing... -
1st November 2019, 18:20
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Closed: Re: Ac induction motor constant speed control
Induction motors are NOT brushed DC motors where you can measure the back-EMF to estimate the speed the motor is turning.
You DO REQUIRE a tachometer. Can be optical, reluctance or magnetic. ... -
1st November 2019, 18:13
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- 11
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Closed: Re: Automatic light control circuit (On-Off)
What c-mitra said above. With dusk and dawn conditions, or in cloudy days, without hysteresis the relay will be chattering.
A LM393 comparator is both ubiquitous and ultra cheap. Use it to build a... -
31st October 2019, 01:17
Thread: forward voltage of LED diode
by schmitt trigger- Replies
- 3
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- 293
Closed: Re: forward voltage of LED diode
Forward voltage drop depends on the LED wavelength.
IR diodes indeed have forward voltages of around 1.7 volt, blue diodes are over 3 volts.
But less than 1 volt?
No. -
26th October 2019, 21:28
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Closed: Re: shunt 24V rail to reference voltage using opamp?
I fail to see how this circuit could work at all.
Both the comparator and the optocoupler are open collector, and without a pull up resistor, the output will always be zero. -
17th October 2019, 22:23
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Closed: Re: Phase current motor measurements with cro
If, and that is a big if, I am understanding you correctly:
You require three clamp type probes, a single differential high voltage probe, and a 4 channel scope.
Connect the high voltage probe... -
17th October 2019, 18:08
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Closed: Re: Getting trigger signal for 555 timer from elevator button.
"I tried two circuits to get low signal to trigger 555 timer .
I tried circuit 2 with 10k for R1 and R2 and i faced a problem . *the led of pc817 always on an this tell the controller the button... -
17th October 2019, 17:59
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[SOLVED]Closed: Re: Generation of 4 Phase Shifted clock Signals
Once upon a time, a complex timing waveform generation like the horizontal and vertical TV sync pulses, were designed using only vacuum tubes. But the sync generator was a refrigerator-sized...
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17th October 2019, 16:30
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Closed: Re: ds1307 Rtc clock running slow by 6 second per day.
In a previous company we had product which sold in +200k/year volumes and which used a DS1307. Produced it for over 5 years, perhaps over a million units total.
Following the app note... -
16th October 2019, 18:38
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Closed: Re: ds1307 Rtc clock running slow by 6 second per day.
And all of those crystals that you have changed, are they different vendors and part numbers?
Did you purchase them from reputable vendors or from e-bay?
Having said this: If you really require... -
15th October 2019, 17:07
Thread: Wiring of DC fans in Series
by schmitt trigger- Replies
- 20
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- 1,420
[SOLVED]Closed: Re: Wiring of DC fans in Series
The current draw of small DC fans do indeed change with rotation. Additionally, you cannot expect the two devices to draw the exact same current, even if they are the same brand and model.
Bryan's...
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