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Milen

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  • Milen commented on Milen's instructable Headphone Amplifier
    Headphone Amplifier

    Exactly in this case there is not any voltage gain. The device can be used for power amplification - that means : when you use a sound source with relatively high output impedance - such as audio DAC for example, you can not load it with low impedance headphones - it will produce very quit sound. Then you will need to use a buffer, which have to match both source and load impedances - this chip performs axactly this function - it has high input impedance to match with the source impedance and low output impedance to match with the low headphones impedance. In this way the maximum power is transferred to the load. Of course there are a lot of other headphone amplifier boards, where the output amplifiers have voltage gain, which even can be increased by change of the feedback resistors. Thi…

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    Exactly in this case there is not any voltage gain. The device can be used for power amplification - that means : when you use a sound source with relatively high output impedance - such as audio DAC for example, you can not load it with low impedance headphones - it will produce very quit sound. Then you will need to use a buffer, which have to match both source and load impedances - this chip performs axactly this function - it has high input impedance to match with the source impedance and low output impedance to match with the low headphones impedance. In this way the maximum power is transferred to the load. Of course there are a lot of other headphone amplifier boards, where the output amplifiers have voltage gain, which even can be increased by change of the feedback resistors. This instructables shows in principle how a headphone amplifier can be constructed using old PC drive. The output product will have voltage gain or it will not have - depends on the chip you find there.

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  • Milen commented on Milen's instructable Cheap and Efficient Desulfator
    Cheap and Efficient Desulfator

    The presented design can be used for both 220V and 110V. The case used is suitable for EU outlet.

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  • GPIB Shield for "Engadino" ("Pinguino")

    In that time I was using the Itead PCB service. I found my login there, but unfortunately it is not possible to download back your design data. I would suggest you to use the toner transfer method and the attached to the project pdf files.

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  • GPIB Shield for "Engadino" ("Pinguino")

    Sorry. There are two problems - all data for this project is lost - it was created years ago and I have formatted my HDD few times. The second problem - the Autodesk owner of instructables site did impossible to upload gerber and zip files more. The only possible way that you can download such data is to use a link to shared project in the PCB manufacturer. I do not remember where the PCB's were done. I will check if I can find the history of thise pcb's stored in some PCB fab account.

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  • Milen commented on Milen's instructable Cheap and Efficient Desulfator
    Cheap and Efficient Desulfator

    I really do not know - because I did not know how it was performing before. Now it works almost as described in the specifications.

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  • Milen commented on Milen's instructable LASER Diode Driver
    LASER Diode Driver

    Hi,Normally the lasers are driven by current generators, but in the cheap pointers batteries from the type 8630 are used. I think that you can adjust one of your converters to give such voltage as in the original.

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  • Arduino Controlled Tiny FM Radio

    I think - yes. If you do not interrupt the power supply of the radio it shall keep the last sent data.

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  • Arduino Nano to Arduino Uno Adapter

    OK. Please read the update on step 3.

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  • Arduino Nano to Arduino Uno Adapter

    I checked also the files there. They also contain this problem. I will modify the flies and upload again the gerber files.

    Hi, There is something wrong in the data.You can try to order direct following this link:https://www.pcbway.com/project/shareproject/Arduin...Until now I did not have any problems with this board, but what I see in their picture is something what is not OK. Cancel this order.

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  • Arduino Nano to Arduino Uno Adapter

    Hi,They should be there. Even twice. One file containing this information is the *.drd, the other is the *.txt file. If you have any doubts - contact the PCB maker if everything is OK.

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  • Milen commented on Milen's instructable AVR ISP Programmer
  • Milen's instructable Web Radio's weekly stats:
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  • How to Modify a XYZ Da Vinci 3D Printer to Work With Replaceable  Nozzles

    Your Job is also nice :-). I see you did a lot of effort to document your work in very professional way.In my case I needed the bed leveling peg, because this procedure was working quite well.RegardsMilen

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  • Arduino Nano to Arduino Uno Adapter

    You are right - you can supply the nano through the adapter board DC jack with voltage till 12V. It appears at Vin pin ( reduced with one diode voltage drop). The 5V are created by the nano's voltage regulator and appear at 5V pins of the arduino and the adapter board.

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  • How to Modify a XYZ Da Vinci 3D Printer to Work With Replaceable  Nozzles

    Sorry. I do not know... But, you can try - the parts are not exepensive compared with the original ones.

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  • Milen's instructable Cheap and Efficient Desulfator's weekly stats:
    • Cheap and Efficient Desulfator
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  • Milen's instructable Analog Front End for Oscilloscope's weekly stats:
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  • Milen commented on Milen's instructable LASER Diode Driver
    LASER Diode Driver

    Hi,The choice of the transistor in this case depends mainly on how much current you want to pass through it and what supply voltage you will use. In this case you have to check the max DC Ids current which the transistor can pass and the breakdown voltage drain-source (this shall be not a problem at all, because it is always higher than the max supply voltage of the op amp). Please read also above about the input capacitance (gate capacitance). For this application you can replace the MOS transistor with bipolar NPN. In this case you will nit have a problem with the capacitive overloading of the op amp. For this project you can use almost every available NMOS or NPN without problems. Keep in mind that it can create a lot of heat if high currents are flowing.

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  • Milen's instructable Assembling AM Radio Receiver Kit's weekly stats:
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  • Arduino Nano to Arduino Uno Adapter

    The pleasure is mine.

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  • Milen commented on Milen's instructable AVR ISP Programmer

    Hi. Shall be OK. The programmer will take as much current as it needs - two amps is in orders higher that is needed.

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  • Milen commented on Milen's instructable LASER Diode Driver

    Hi,This circuit works in DC mode. It wound be too slow to try to modulate it. I would suggest to use some dedicated laser diode driver chip. For example you can look here:https://www.analog.com/en/parametricsearch/10770or to search Aliexpress for some laser diode driver board :-)RegardsMilen

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  • Milen's instructable USB Switch Improvement's weekly stats:
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  • Milen commented on Milen's instructable USB Switch Improvement

    May be you can try to bridge (parallel) the tracks with thicker wire?

    Hi,I have connected my phone to the usb switch. The phone gave me the message: "Charging slowly with usb. Connect to standard charger to charge faster"

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  • Milen commented on Milen's instructable USB Switch Improvement

    Hi,Until now I used the switch only to print few pages. I did not have any problems. May be after some time, when the switch contacts oxidise I will have similar problems. In your case may be a USB hub would work better.RegardsMilen

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  • Hi Cwamagalhaes,I was not able to download them either.I have redirected the problem to the site support and I hope soon to have positive answer. Thank you for reading the instructable and the nice words.RegardsMilen

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  • Milen's instructable Speakers Revival's weekly stats:
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  • Milen entered Speakers Revival in the Trash to Treasure contest
  • Milen's instructable Fiat Lux's weekly stats:
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  • Milen's instructable RF Signal Generator's weekly stats:
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  • Milen commented on Milen's instructable RF Signal Generator

    Why you do not write instructable about this?

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    • Cheap Tester for Voltage Regulators
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  • This project is Addendum to this: https://www.instructables.com/Digital-multimete...The whole schematic for the main project and the addendum is here:https://cdn.instructables.com/FOZ/DNW9/JFIIXT5Q/FO...On the black PCB is soldered only the part marked with red square - the milliohm part.If you want to have the full functionality - you have to solder also the parts from the main project.

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  • Hi,You can use each small signal, low Ron, NMOS. For example;2N7002WNTNS3193NZ (difficult to solder by hand)NTUD3170NZ - this i duall (two NMOS devices in one package)etc...

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  • Milen commented on Milen's instructable Building POF Home User Network

    Hi,The loses are higher compared with the glass fiber - that is the reason for the limited speed and distance.When this work was written the private POF networks were newly born. Mow I suppose that there also some progress happened, but now I am not in this businesses and I do nit know the current state.Please google and find it by yourself.regardsMilen

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  • Milen's instructable Hack a USB Card Reader's weekly stats:
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  • Hi. Nice toy.I have small correction for Germany - before green the red and yellow are on together,

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  • Hi,C1 is 100nF filtering cap at the input,C0805 is the size of SMD capacitor. For more info you can go for example here: http://www.kemet.com/Lists/ProductCatalog/Attachme...RegardsMilen

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    • How to Modify a XYZ Da Vinci 3D Printer to Work With Replaceable  Nozzles
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  • Hi,From 100uF to 1000uF. Can be also outside this range. Or if you have good filtered supply source - you can omit it.

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    • Assembling of LM386 DYI Stereo Amplifier Kit
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  • Milen commented on Vishwas Navada's instructable Electronic Chameleon

    Hi,Nice project.But I have the following remarks:You code does not correspond to the video you show - on the video you light up all LED's of the strip, you code turns on only single one. (Ok...this can be easily corrected).Most problematic I find you circuit- simple following it can create a lot of complications.The first problem - the LED strip DO pin instead DIN pin is connected to the arduino data pin. It could work ( I did not try it, but in common it is misleading and can create problems)Second problem - in your circuit the TCS3200 OE pin is connected to the arduino 3.3V pin.Without checking I connected the sensor to my Arduino Duemilanove board and I almost burned out the FTDI FT232RL. This type of connection loads extremely the build in the chip 3.3V voltage regulator and the chi…

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    Hi,Nice project.But I have the following remarks:You code does not correspond to the video you show - on the video you light up all LED's of the strip, you code turns on only single one. (Ok...this can be easily corrected).Most problematic I find you circuit- simple following it can create a lot of complications.The first problem - the LED strip DO pin instead DIN pin is connected to the arduino data pin. It could work ( I did not try it, but in common it is misleading and can create problems)Second problem - in your circuit the TCS3200 OE pin is connected to the arduino 3.3V pin.Without checking I connected the sensor to my Arduino Duemilanove board and I almost burned out the FTDI FT232RL. This type of connection loads extremely the build in the chip 3.3V voltage regulator and the chip heats up very much to levels when its temperature protection triggers. The OE pin of TCS3200 shall be connected to GND instead!I will suggest you when publishing any circuits to check their functionality preliminary, because you can create a lot of headaches to the others trying to repeat them.Best RegardsMilen

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    • Miliohm-meter Arduino Shield - Addendum
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  • Hi,I had some desoldered from some old board.But u could use these:https://www.aliexpress.com/item/5pcs-Rotary-encode...or thesehttps://www.aliexpress.com/item/10pcs-Rotary-encod...os something similar

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  • Milen commented on Milen's instructable Function Generator

    Hi,I have added the schematics at step 2. I hope that is the last version.

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  • Milen commented on Milen's instructable Tiny FM Radio

    Hi,Now a power source from 2.7 to 5 V can be used. If you put some linear voltage regulator from 3.3V or 5V - then the input voltage can be till 35V. With some minimal changes the power supply can be reduced to 2.5V. With more drastic schematic changes the power supply can be reduced to 1.8V. This requires change of the used chips and also in the control approach.

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  • Milen's instructable AM Modulator - Optical Aproach's weekly stats:
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  • Hi,Try to use rail to rail single supply op amp in inverting configuration between the voltage input chain and the ADC input. The non inverting input connect to a stable filtered voltage reference close to vdd/2, and set the gain such that if your input volatile is -55V the opamp output trends to vdd, and if your input is voltage is +55Vm the output goes close to gnd. You have to adjust the reference voltage a little to make the output swing symmetrical. I would advice to use spice simulator (like LtSpice - free download from the site of Analog devices. There you can find a lot of opamp models, which can be used for this purpose)

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  • Hi,This a picture of the back side of the LCD screen. These are the controller chips. The display is standard 16x2 character LCD. Under desire also graphical one can be used.

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  • Hi,The right one could work. I would remove R2 if possible.Practically this measurement is not fully identical with the 4 probe measurement. There the main idea is to pass some known current and to measure the voltage drop, here the current is defined by your resistors and the applied voltage.If you remove the R2 than you can measure precisely the voltage asVin = (R6+R7)/R7*Vmeas, where Vin is the battery voltage (input voltage), Vmeas is the sampled voltage.The current sourced by the battery can be estimated as Imeas+Vin/(R6+R7),where Imeas is the measured current and Vin is the calculated voltage(see above).If R2 is your load and you can not omit it, then the formulas will change.R2 must be known and have to be inserted in the calculations.What is the tool that you use for drawing the c…

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    Hi,The right one could work. I would remove R2 if possible.Practically this measurement is not fully identical with the 4 probe measurement. There the main idea is to pass some known current and to measure the voltage drop, here the current is defined by your resistors and the applied voltage.If you remove the R2 than you can measure precisely the voltage asVin = (R6+R7)/R7*Vmeas, where Vin is the battery voltage (input voltage), Vmeas is the sampled voltage.The current sourced by the battery can be estimated as Imeas+Vin/(R6+R7),where Imeas is the measured current and Vin is the calculated voltage(see above).If R2 is your load and you can not omit it, then the formulas will change.R2 must be known and have to be inserted in the calculations.What is the tool that you use for drawing the circuit?Do you use some spice simulator?I would suggest you to simulate the circuit before building it.In this way you can observe all voltage and currents and to see their behavior.here is a nice free spice simulator, which you could use , in the case you do not have one : http://www.linear.com/solutions/ltspice

    HI,as I see on your circuit, the resistor R1 I connected from both sides to Arduino GND - that means it is shorted. No voltage drop exist over it.That is the reason your voltage is always zero.Re-arrange the circuit - I would suggest to put R1 from the left side of R3.You will have some small voltage measurement error, but you can cancel it by the software. Also the current should affected by the additional voltage divider R6,R7...but this can be also corrected.

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  • Hi,You can - but you have to merge both procedures (for voltage and current measurements) in one and to display both values.

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  • Hi,In the state it is now - no.hardware or software changes must be implemented.Software - you could make FFT and find the signal amplitudeHardware - the voltage must be rectified, filtered and measured as DC - further calculations must be done to receive the RMS value.

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  • If you apply all current, voltage and resistance simultaneously - you can measure each of them switching by the main menu.

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  • Hi,I did not produce current. It is flowing by itself. Imagine a wire through which a current is flowing. We cut the wire and put the ampermeeter between two cut parts. That means - we short again both pieces but through 1Ohm resistor. (we suppose it does not effect the current value). The current flows again. But it creates a voltage drop over the 1Ohm resistors. That is what we measure.

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  • Hi,The input for the amperemeter is current, but there is a current to voltage conversion inside the DMM - The current passing through 1 Ohm resistor creates voltage drop. And practically what the DMM does is measuring this voltage, but not the actual current. You can see the schematics of the amperemeter at step 5. Because the voltage is measured (which is product of the current passing through 1 Ohm resistor), there is not a big difference between the voltmeter and the amperemeter in the code.Only the calculations of the results, which shall be shown on the screen are different. The units also.The procedure performing current measurement is A_500() - you can scroll the code and find it easy.

    The opamp is supplied by the common supply (5V). Its ground is the common ground. The amperemeter is used in series as usual amperemeter. Please read step to for more precise explanation.

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  • Hi,Practically all amperemeters work in similar way - the current which must be measured is passed through small resistor. It creates a voltage drop over the resistor, and this voltage drop is measured by the embedded in the multimeter voltmeter. Further a calculation of the current is done : known are the resistor value and the voltage drop over the resistor and according the Ohm's law I=V/R.In my case I use the same approach - the measured current is passed through 1 Ohm resistor. After that I use amplifier by 10 - I multiply the voltage drop over the resistor 10 times. For that purpose an operational amplifier in noninverting configuration is used (the input resistance of this configuration is practically infinity).So a current of 500 mA flowing through 1 Ohm resistor creates 0.5V vol…

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    Hi,Practically all amperemeters work in similar way - the current which must be measured is passed through small resistor. It creates a voltage drop over the resistor, and this voltage drop is measured by the embedded in the multimeter voltmeter. Further a calculation of the current is done : known are the resistor value and the voltage drop over the resistor and according the Ohm's law I=V/R.In my case I use the same approach - the measured current is passed through 1 Ohm resistor. After that I use amplifier by 10 - I multiply the voltage drop over the resistor 10 times. For that purpose an operational amplifier in noninverting configuration is used (the input resistance of this configuration is practically infinity).So a current of 500 mA flowing through 1 Ohm resistor creates 0.5V voltage drop x10 = 5V(as big as the supply voltage of the arduino and as its reference voltage used .for the analog to digital conversion.). Amplifying the voltage drop over the resistors makes the resolution of the measured voltage 10 times better.As you know the arduino main chip has embedded 10 bit ADC.The amplified voltage is measured by it - using the AnalogRead() command. I measure it 16 times. Then I sum all these results and divide the sum by 16. In this way I receive some average value, what improves the accuracy of the measurement - removes the noise in some degree and improves the resolution. This value is still digital word (big from 0 to 1023). And finally I calculate the real current:the digital word I divide by 1024 - this gives the ratio measured voltage divided by reference voltage. After that the division is multiplied by the reference voltage (in our case the ATMEGA328 supply voltage) and we have the needed measured voltage. We divide it by 10 to cancel the amplification, and divide it by 1 Ohm (in my case - it can be also different value - depends on the resistor used) and we have finally the needed current.

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  • You can by a 10:1/1 probe and you problem is solved. :-)

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  • Thank;s. You hope you will not go in my way - to burn out the chip and to replace it :-). Good luck!

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  • Milen commented on Milen's instructable Audio Mixer

    The input resistance depends on the potentiometers used.The input resistance of the mixer amplifier is 20k (for audio). As it is, it can work also with line level signals. If the gain is not enough - you can change it for both stages (increasing the feedback resistors), but you have to check what is the recommended gain for the output amplifier. If you want to increase drastically the input resistance, you can change the configuration of the input stage to non-inverting. The output impedance of the mixer is low. Not more than 100 Ohm for 20 Hz signal. It can drive both - headphones and line.

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  • Milen commented on Milen's instructable Audio Mixer

    From left side these caps see the vdd/2 voltage.If no signal applied from right side they see the ground potential through the pot.Of course, the potential from left side cna become more positive, but normally the signal source is also AC coupled, which defines the DC potential at the capacitors left side always to 0.

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  • Milen commented on Milen's instructable Audio Mixer

    For me seems to be OK.

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  • Milen commented on Milen's instructable Audio Mixer

    Hi MartinI34,You can remove the headphone amp.You have to create additional reference voltage for the first amplifier - voltage divider - supply/2 and to keep the filtering cap (C11).C9 and C10 prevent flowing of the DC current through the load (the headphones) - they pass only the AC (the signal). If you omit the headphone amplifier, you have to use also such AC coupling capacitors between the mixer and your device - you can take the signal after the capacitors C7,C8.

    That is true. You have to create virtual ground. In this case we use single supply of 5 V. The best voltage for the virtual ground should be 2.5V.That means - you connect two identical 5 to 10 K resistors in series between the 5V and the ground. At the middle point you put capacitor (1 uF) and connect this node to the pins 3 and 5 of the opamp as virtual ground. That will force the AC signal to dance around this voltage :-).Seems that mcp6022 is a nice alternative for this purpose.

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  • Milen commented on Milen's instructable Building POF Home User Network

    Practically the POF does not contain any metal wire to attract the lightnings and it does not conduct electrical current. In practically impossible case, when the POF cable is wet it could be conductive, but in this case everything around would be...I do not know how protected is the cable against the sunlight - may if exposed to direct sun rays, its external plastic shield could become breakable - in this case may you have to use some plastic tube. But I think that it would be not needed - the cable by itself should enough resistant.

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  • The varistors are for high voltages. In all cases the simplest solution is to use some 5.6V zenner diode.

    Hi,I took a look on the datasheets.The serial diode is optional.You can use NCP346 without it and without problems.

    Sorry,I did a mistake.None of the listed chips will work as input voltage protection for the DMM if connected as shown in their datasheets.Problems:1) They must be supplied by the common DMM supply - not by the input voltage, because it could drop even to 0V and the current is limired.2) If only NMOS or PMOS switch used - it will cut some part of the input voltageswhen PMOS used - it will pass only the voltage (rough said) >2.5V, if NMOS only used it will pass voltages <2.5V.So called transmission gate must be used ( parallel connection of NMOS and PMOS) switches controlled by the signals with opposite polarity.That means - at the output of (let's say) NCP346 additional inverter must be connected and it has to control an NMOS switch connected in parallel with the PMOS switch contro…

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    Sorry,I did a mistake.None of the listed chips will work as input voltage protection for the DMM if connected as shown in their datasheets.Problems:1) They must be supplied by the common DMM supply - not by the input voltage, because it could drop even to 0V and the current is limired.2) If only NMOS or PMOS switch used - it will cut some part of the input voltageswhen PMOS used - it will pass only the voltage (rough said) >2.5V, if NMOS only used it will pass voltages <2.5V.So called transmission gate must be used ( parallel connection of NMOS and PMOS) switches controlled by the signals with opposite polarity.That means - at the output of (let's say) NCP346 additional inverter must be connected and it has to control an NMOS switch connected in parallel with the PMOS switch controlled directly by the "OUT" terminal of the chip.So.... the circuit becomes more and more complicated :-)

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  • May be NCP346 is not the most suitable circuit for a voltmeter.It has to have only low Ron switch. Check the others.The serial diode would effect the correctness of the measurement because of the voltage drop on it.Normally each multimeter should have some protection on the input.The protection which I use is the simplest and may be most used.As common the DMM devices use dedicated chips (ASIC) and I suppose the protection is embedded directly inside them - in all cases it has to based on some voltage clamping circuit, or circuit similar to mentioned before chips.

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  • Hi ArezkiLAs I remember I bought 50 pcs 5.6V zenner diodes and I have chosen one of them having the smallest reverse current at 5V.There are also another possibilities to protect the input against HV.There exist special overvoltage protection circuits containing MOS switch with very low Ron, which observe the input voltage and if it becomes higher then desired interrupt the connection. All depends on that how much you want to complicate the device :-)Examples of such circuits: NCP346, STBP112,NUS3046MN...and a lot of others.You can use 5% resistors, The introduced error you have to correct further by the software trimming.RegardsMilen

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  • Hi,you can not feed current inside the analog pin. You can apply only voltage - not more than the supply voltage+0.5V.The maximum frequency is determined by the max sample rate:76.9kSPS of the ATMEGA328 ADC and the Nyquist requirement ----> around 38,5 kHz.You can put a fuse from the type that you like, but its max current must be proper chosen

    Hi,as designed it measures 500 mA max current - that should be the fuse rating. If you want to measure higher current ´then you have to change also the resistor. You could add also input for higher currents with different resistor and can use also different arduino analog input.

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  • Hi Witgood,I never went so deep inside the hardware, except for the power supply part.I could try to find out which MPU/MCU is used. Also if any operation system is installed. This could be Openwrt. Using an USB to TTL serial converter ((based on FT232, PL2303, CH340G or etc.) you could try to communicate with the board - you have to search for (TX,RX) labels on the board and try to connect there.As terminal you could use Putty. May be you have to try different communication speeds. If you find some linux installation - you could try to update the firmware...You could also try to run some memory tests...It could be an interesting play.Please, if you find some additional info - share it here to be available for all interested.RegardsMilen

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