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Type: Posts; User: FvM
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Yesterday, 15:48
Thread: Unknown formal identifier in VHDL
by FvM- Replies
- 5
- Views
- 136
Closed: Re: Unknown formal identifier in VHDL
"(vcom-1484) Unknown formal identifier" indicates that the LHS of a port association in the instantiation doesn't exist. The error message is the same if you are instantiating components or design...
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Yesterday, 14:07
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- 13
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- 352
Closed: Re: How to implement a transfer function with discrete components
Yes, that's what the circuit implements.
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Yesterday, 12:44
Thread: adc7715 simulation in proteus
by FvM- Replies
- 2
- Views
- 160
Closed: Re: adc7715 simulation in proteus
The shown simulation circuit is surely not working. Floating DIN, continuous SCLK, that's not how the device can be operated. Review datasheet chapter Digital Interface for details.
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Yesterday, 11:34
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- 13
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- 352
Closed: Re: How to implement a transfer function with discrete components
Obviously. Can be implemented with basic active circuit.
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15th February 2019, 16:38
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- 3
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- 160
Closed: Re: Any good optocoupler IC for voltage sensing with single voltage source
The question makes sense if it refers to ACPL series of isolation amplifiers and sigma-delta modulators. However there's none with built-in power transmission to the primary side. Analog AD202 is an...
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15th February 2019, 12:27
Thread: cascading filter after a 2 poles sallenkey
by FvM- Replies
- 46
- Views
- 691
Closed: Re: cascading filter after a 2 poles sallenkey
The OP claimed the filter should "not change the phase till 25-30kHz", see the discussion in my previous post #21. If we take this serious, Butterworth won't be acceptable.
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15th February 2019, 10:01
Thread: cascading filter after a 2 poles sallenkey
by FvM- Replies
- 46
- Views
- 691
Closed: Re: cascading filter after a 2 poles sallenkey
Yes, the f0=40 kHz, Q=0.5 block can work well for 6th order Butterworh with 40 kHz cut-off. But Butterworth doesn't meet the linear phase requirement in post #18. A 40 kHz Bessel filter would, but it...
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15th February 2019, 09:49
Thread: Ac motor speed control
by FvM- Replies
- 19
- Views
- 1,295
Closed: Re: Ac motor speed control
"The delay" in the present code doesn't change the trigger time. Triac trigger pulse must be delayed relative to zero crossing. And you need a zero crossing detector that works equally for positive...
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14th February 2019, 23:02
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- 3
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- 107
Closed: Re: Looking for BJT that has very low collector leakage current.
Would you mind to tell target leakage, capacitance and voltage numbers?
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14th February 2019, 22:47
Thread: cascading filter after a 2 poles sallenkey
by FvM- Replies
- 46
- Views
- 691
Closed: Re: cascading filter after a 2 poles sallenkey
Besides ambiguous phrasing, I don't get the idea behind reusing the post #1 bi-quad block in a higher order filter. The specific complex pole pair either fits the intended overall characteristic or...
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14th February 2019, 22:22
Thread: AVR: SPI using interrupt
by FvM- Replies
- 7
- Views
- 174
Closed: Re: AVR: SPI using interrupt
Not sure if the poster shares your sense of humour. Anyway, I agree that the coding style should be avoided.
Editing is only enabled 30 minutes after posting. Consider that others already read... -
14th February 2019, 00:35
- Replies
- 12
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- 821
Closed: Re: data and clock synchronization using 74HC4046 PLL
Many people, I presume, including myself. But I guess, you wanted to ask if anyone has a working CDR circuit based on 4046?
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14th February 2019, 00:22
Thread: Quick way for an adjustable low pass filter
by FvM- Replies
- 17
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- 330
Closed: Re: Quick way for an adjustable low pass filter
If adapting signal levels to the SC filter range is your only problem, you are really a lucky guy. That's an - excuse me - almost trivial problem. Yes, you'll use an attenuator in front of and an...
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13th February 2019, 19:18
Thread: cascading filter after a 2 poles sallenkey
by FvM- Replies
- 46
- Views
- 691
Closed: Re: cascading filter after a 2 poles sallenkey
The circuit in post #1 doesn't implement a Bessel filter, it's roughly a critically damped (Q = 0.5) filter, very droopy as already stated. Looking primarily for a sharper corner and higher stop...
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13th February 2019, 13:34
Thread: Quick way for an adjustable low pass filter
by FvM- Replies
- 17
- Views
- 330
Closed: Re: Quick way for an adjustable low pass filter
A state-variable filter can act as bi-quad building block. https://en.wikipedia.org/wiki/State_variable_filter Potentiometers connected before Rf1 and Rf2. Zero frequency however doesn't work,...
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13th February 2019, 13:27
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- 5
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- 345
Closed: Re: What does the LOOP GAIN's phase and gain margin say about the CLOSED LOOP respons
No. GM holds more or less the same information as PM. See previous answer by sutapanaki.
For simple amplifier characteristics, e.g. integrator with additional poles, relation between PM, GM and... -
13th February 2019, 13:06
Thread: Quick way for an adjustable low pass filter
by FvM- Replies
- 17
- Views
- 330
Closed: Re: Quick way for an adjustable low pass filter
Instead of "0 to 10 kHz" you should give a feasible frequency range specification. A 4th order filter that keeps characteristic over frequency range requires four adjustable gain elements, either...
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13th February 2019, 09:36
Thread: cascading filter after a 2 poles sallenkey
by FvM- Replies
- 46
- Views
- 691
Closed: Re: cascading filter after a 2 poles sallenkey
Cut-off frequencies are not always calculated for -3 dB (half power point) attenuation. The Okawa tool apparently uses -6dB point, which explains the differences.
??? Of course you can modify... -
12th February 2019, 18:49
Thread: cascading filter after a 2 poles sallenkey
by FvM- Replies
- 46
- Views
- 691
Closed: Re: cascading filter after a 2 poles sallenkey
A 4th order transfer function can be decomposed into two 2nd order function, the same with higher order filters. Filter design tools do already calculate the individual second order blocks (bi-quads).
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12th February 2019, 11:13
Thread: RTC PIC16F877A without ds1302
by FvM- Replies
- 4
- Views
- 138
Closed: Re: RTC PIC16F877A without ds1302
Using T1OSC with a 32 kHz watch crystal is the next best solution, however PIC16F877 has not low power features to operate the RTC battery powered. Even PIC processors with dedicated RTC unit can't...
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12th February 2019, 11:05
- Replies
- 1
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- 236
Closed: Re: how to install workloads of C++ tools in the Visual Studio 2017 Express
You are asking about std::cout? Did include the respective header <iostream>?
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10th February 2019, 22:33
Thread: Good wire for small antenna
by FvM- Replies
- 4
- Views
- 178
Closed: Re: Good wire for small antenna
Metal tubes are the usual choice.
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10th February 2019, 22:08
- Replies
- 4
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- 199
Closed: Re: High voltage input linear regualtor using IGBTs?
Why do you think so?
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10th February 2019, 21:59
Thread: USB multiplexer via FPGA
by FvM- Replies
- 1
- Views
- 131
Closed: Re: USB multiplexer via FPGA
It's not feasible with FPGA, it has neither analog switch features nor an USB 2.0 PHY. Besides MAX4999, there's a number of high speed analog signal switches that can do the job.
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10th February 2019, 12:26
- Replies
- 2
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- 133
Closed: Re: Question about electric and magnetic Hertizian dipoles
Symmetry considerations seem to contradict your assumption at first sight. In any case phase and magnitude relation of both sources matter for the superimposed characteristic.
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