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  • rgco's instructable Portable Precision Stroboscope's weekly stats: 13 days ago
    • Portable Precision Stroboscope
      372 views
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      1 comments
  • rgco commented on rgco's instructable Arduino Waveform Generator13 days ago
    Arduino Waveform Generator

    Done! beware that there may be mistakes in it! I drew it up after making the device and did not do any tests or simulations (if that is at all possible with Fritzing...)

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  • rgco's instructable USB Floodlight's weekly stats: 16 days ago
    • USB Floodlight
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  • rgco commented on GreatScottLab's instructable Make Your Own LED Stroboscope18 days ago
    Make Your Own LED Stroboscope

    Thanks Scott! You inspired me to make it into a portable device:https://www.instructables.com/id/Portable-Precisio...

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  • rgco commented on rgco's instructable USB Floodlight21 days ago
    USB Floodlight

    Good point, I added it. Thanks!

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  • rgco entered USB Floodlight in the Make it Glow Contest 2018 contest 21 days ago
  • rgco posted an instructable USB Floodlight22 days ago
  • rgco commented on rgco's instructable Arduino Waveform Generator5 weeks ago
    Arduino Waveform Generator

    The schematic and breadboard should by construction match up (Fritzing makes both from the same input) but I agree they are not super clear!From what you say I suggest to debug in steps: if you disconnect the R2R from the rest, does it give a waveform with minima-maxima of 0-5V? If not, the issue is likely the R2R bridge. If yes, reconnect the attenuator. Depending on the setting the max should now be in the range 0-4V. Then the unamplified (buffered) output, then the amplified output.

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  • rgco commented on rgco's instructable Arduino Waveform Generator6 weeks ago
    Arduino Waveform Generator

    Thanks for the tip! I must say I was surprised how well the R2R DAC works even without any special measures: I had started to make a list of resistor values to make matched pairs, but then got bored and thought I could adjust afterwards if needed. Instead there is no sign of any steps in going e.g. from 127 to 128. Also the soldering wasn't too bad since the schematics almost matches the pin layout, so there is no need for bridges, and resistors are easy anyway since they are symmetric and temperature-resistant. But I'll definitively consider for future projects!If you don't need the highest frequencies, the waveform array can indeed be extended to e.g. 1024 bytes using a 16-bit integer as index. The number of clock cycles will need to be redetermined (easiest by trial and error) but I ...

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    Thanks for the tip! I must say I was surprised how well the R2R DAC works even without any special measures: I had started to make a list of resistor values to make matched pairs, but then got bored and thought I could adjust afterwards if needed. Instead there is no sign of any steps in going e.g. from 127 to 128. Also the soldering wasn't too bad since the schematics almost matches the pin layout, so there is no need for bridges, and resistors are easy anyway since they are symmetric and temperature-resistant. But I'll definitively consider for future projects!If you don't need the highest frequencies, the waveform array can indeed be extended to e.g. 1024 bytes using a 16-bit integer as index. The number of clock cycles will need to be redetermined (easiest by trial and error) but I suppose it won't add more than 10 cycles.

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  • rgco commented on rgco's instructable Arduino Waveform Generator6 weeks ago
    Arduino Waveform Generator

    Ah sorry, I missed that one: the encoder I used has 5 pins, 3 on one side, 2 on the other side. The side with 3 pins is the actual encoder, the side with 2 pins is the integrated pushbutton.On the 3-pin side, the central should be connected to ground, the other two to D10 and D11.on the 2-pin side, one pin should be connected to ground and the other to D12.

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  • rgco commented on rgco's instructable Arduino Waveform Generator6 weeks ago
    Arduino Waveform Generator

    It is 1 microfarad. It is not essential but helps to smooth the power to the opamp. I would recommend to put the largest ceramic capacitor that you have. Most sets go up to 100nF and that is probably fine. I once bought a bag of 100 1microfarad ceramic capacitors for less than 1 euro and they come in great everytime an IC is used in a project. I would avoid electrolitic capactors here because their capacitance is very much reduced at high frequencies.

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  • rgco commented on rgco's instructable Arduino Waveform Generator7 weeks ago
    Arduino Waveform Generator

    I used an MT3608, which cost 30euro cents on Aliexpress. The LTC3105 was the only step-up module that I could find on Fritzing (the text has been updated to make it more clear). I don't think it's critical, it only needs to power 20mA or so for the opamp.Glad you like it. Let me know in case you make it!

    Glad you like it. Let me know in case you make it!

    500kHz undistorted sine wave with Arduino would be hard. The interrupt handling does not cost any time, so a second Arduino would not help. One thing that comes to mind is to use the timers to generate a fast block wave and then use an analog filter to turn it into sine. But the frequency can't be tuned precisely. There are other instructables out here that describe how to use an external chip, e.g MAX038 and control it with an Arduino. That'd probably give a much more performing device

    Hi, yes, I confirm the scope was bought as shown, I paid 13EUR online. There are kits as well but after watching a video of how to assemble that, I figured it was worth to spend a few euros more for the assembled scope.Actually I do have an instructable for how to use an Arduino as a scope ( https://www.instructables.com/id/Another-Arduino-O... ) which has a plus that it's multichannel. However the sampling rate is lower (77ks/s vs 1000ks/s) and it's a bit of a hassle to use the laptop screen as a scope display

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  • rgco's instructable 48W Resistive Load's weekly stats: 7 weeks ago
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  • rgco commented on rgco's instructable Simple Arduino Metal Detector5 months ago
    Simple Arduino Metal Detector

    Glad it works and thanks for the feedback!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector6 months ago
    Simple Arduino Metal Detector

    It's a headphone plug for 3.5mm headphones

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  • Measuring the IV Curve of Semiconductors With an Arduino

    Hi, did you try changing Vmax=5.0 to Vmax=1.0?

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector6 months ago
    Simple Arduino Metal Detector

    Hi, There is no straightforward gain from having more windings. More windings means higher inductance so somewhere else that needs to be compensated to achieve values in the right range for the ADC, like a higher value for the capacitor. I'd expect the performance to change, since the frequency spectrum of the pulse changes, but it's not clear whether things improve or get worse. When I built it this was all the wire I had, so I couldn't really experiment. In the meanwhile, I recovered enamel wire from an old TV, so it'd be interesting to try out some different coils!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector6 months ago
    Simple Arduino Metal Detector

    Glad you made it work! I agree it's hard to make it work reliably, and the autocalibration algorithm is a bit sloppy. One day I should pick it up and try to improve things a bit. In the meanwhile, I invite you to play a bit with the settings and the code and see if you can make it work better for your purpose. Cheers,

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector7 months ago
    Simple Arduino Metal Detector

    Your logfile output looks good to me! from that I expect it to work similarly as in the video...

    To understand the problem I need to see all numbers from the debug: The main thing though is that the 2nd and 3rd column have fairly constant numbers in the range 200-300. If not the number of pulses or the capacitor value, or the coil may need to be changed

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector7 months ago
    Simple Arduino Metal Detector

    Hi, I noticed this as well, here's my hypothesis: any conductor at high frequencies behaves as a diamagnetic due to the eddy currents (like those aluminum disks that get launched when discharging a capacitor on an electromagnet). So for some materials that are only weakly ferromagnetic, it may be that the effect of the eddy currents (lower inductance) may be stronger than the effect of the ferromagnetism (higher inductance).

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  • rgco commented on rgco's instructable Multichannel Arduino Oscilloscope7 months ago
    Multichannel Arduino Oscilloscope

    Sorry I'm of not much help here. I found the up-and-down communication part between the computer and the Arduino the hardest part to grasp. It kind-of worked without implementing a robust communication protocol..

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  • Measuring the IV Curve of Semiconductors With an Arduino

    Hi, it looks like you have a stricter (newer) version of Processing than I did. 'prevx' and 'prevy' were used to draw lines between the points, but later I found results were better without, and thus commented out the line drawing. Try comment out all the other lines that use prevx and prevy (there are only two more) and it might work. Cheers!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector8 months ago
    Simple Arduino Metal Detector

    You mean in series? yes should be OK, also in parallel. The inductance changes in a similar way as for a single coil...Although I wouldn't see what's the advantage?

    Hi, honestly I haven't touched it since a year, I will post an update in case I look at it again and find some ways to improve the sensitivity. But this type of detector will always be sensitive only to conductors close to the centre of the coil. Best wishes

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  • Blink a LED With Blynk App (Wemos D1 Mini Pro)

    Thanks! It worked in one go!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector8 months ago
    Simple Arduino Metal Detector

    I didn't have a long enough strand, so connected two together, that's all!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector9 months ago
    Simple Arduino Metal Detector

    To detect metal at a distance is MUCH harder than the simple inductance method done here. I think those metal detectors work like radar: send a focussed pulse and look for the reflection. It's a completely different kind of hardware....

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector9 months ago
    Simple Arduino Metal Detector

    The value of the variable 'diff' quantifies the strength of the signal so that could be used.

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  • rgco commented on rgco's instructable Heating Pad for Cat9 months ago
    Heating Pad for Cat

    What voltage was it? I kept it at low voltage for a reason!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector10 months ago
    Simple Arduino Metal Detector

    Nothing, the audio output is on pin 10...

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector10 months ago
    Simple Arduino Metal Detector

    Hi, just run the buzzer straight from pin 10, without series resistor. Good luck!

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  • rgco commented on jasperoprel's instructable Arduino RFID Maze Game10 months ago
    Arduino RFID Maze Game

    True, I also first used the 8x8 matrix that came with a starter kit without controller (actually without anything, just connecting 16 pins straight to 16 IO pins). It truly is a lot easier with the 7219, so much that they can be run from an 8-pin ATtiny. Also expanding to 2 or 4 displays becomes almost trivial. Keep the good work up!

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  • rgco commented on rgco's instructable Heating Pad for Cat10 months ago
    Heating Pad for Cat

    I have outlined several safety measures right at the introduction, and they are repeated in the individual steps. Maybe if the person to whom this accident happened had had access to instructions on how to build it safely, it would not have ended up so badly... Anyway, your point is well taken and I'll add an extra warning, thanks for your feedback!

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  • rgco's instructable High-speed Clock for Slow-motion Videos's weekly stats: 10 months ago
    • High-speed Clock for Slow-motion Videos
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  • rgco commented on jasperoprel's instructable Arduino RFID Maze Game10 months ago
    Arduino RFID Maze Game

    Nice job! wouldn't it be easier (fewer connections!) to use an 8x8 LED matrix run by a MAX7219 chip? Complete modules are sold online for under a euro and they only require 3 connections with Arduino pins.

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  • rgco entered Heating Pad for Cat in the Sew Warm Contest 2018 contest 10 months ago
  • rgco commented on robives's instructable Wire Worm Gear11 months ago
    Wire Worm Gear

    Very instructive and opening up immagination for for. Will try to make this with my kids on a rainy day. Voted!

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  • rgco commented on ryan422's instructable Easy Acoustic Levitator11 months ago
    Easy Acoustic Levitator

    Nice, and so simple. I am going to try this! You got my vote.

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  • rgco commented on rephus's instructable Live Picture Frame With Raspberry PI11 months ago
    Live Picture Frame With Raspberry PI

    Nice! I put it on my to-make list. Time to start dismantling my oldest laptop! You got my vote.

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  • rgco's instructable Toothbrushtimer With the ATtiny13's weekly stats: 11 months ago
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  • rgco commented on rgco's instructable Simple Arduino Metal Detector11 months ago
    Simple Arduino Metal Detector

    Sorry for the late reply. No idea if it still matters! You will probably need to rewrite the code, but it should become simpler. The biggest difficulty I had with the code was to have an algorithm to follow small changes but to trigger on big changes!It may be sufficient to remove the 4 lines that start with 'if(skip>64)' because those trigger a recalibration when there has been a change for a long time. Good luck!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector11 months ago
    Simple Arduino Metal Detector

    Yes, the capacitor will charge 10x slower, so you will either have to use a coil with a large inductance (larger diameter or more windings) or make more pulses. Try building it and running in debug mode, then increase the number of pulses till you get an ADC count of about 10. Good luck!

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  • rgco entered Toothbrushtimer With the ATtiny13 in the Arduino Contest 2017 contest 11 months ago
  • rgco entered Toothbrushtimer With the ATtiny13 in the LED Contest 2017 contest 11 months ago
  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    Hi, I'm afraid the sensitivity won't increase by pushing more current through. For measuring inductance no large currents are required, just like for a precision measurement of a resistor your multimeter uses just microamps.I can see several ways to improve the sensitivity, most have come up in the other comments:* use the 1.1V reference to use the 10-bit ADC scale more effectively* make the coil part of an oscillating LC circuit and measure its frequency.* make a pulse-induction metal detector.You are probably thinking of the latter. But a pulse-induction metal detector is a very different thing. It takes big current, fast switching (MOSFETs, not relays), precise timing, careful coil design etc, and probably a good oscilloscope to do the development. Cheers!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    Hi, I saw clear opposite-sign response when putting a iron wrench and also when putting a box of staplers.It doesn't come out so well in the video, but you see it starts flashing blue (lower inductance) for some metals and green (higher inductance) for others.I would suggest to try a few more iron-based object. There is a large variety of the magnetic susceptibility depending on the precise type of alloy and how it's been forged or melted.

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  • rgco's instructable Fix and Upgrade a Cappuccino Mixer's weekly stats: 1 year ago
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  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    Time is something that the Arduino can measure with very high precision: it has a pretty stable crystal and the timers can be set up to measure with a resolution of a single clock cycle (1/16th of a microsecond). The length of a single LC pulse won't be very accurate (10^-3 for a single pulse of a 16kHz signal). But keeping track of multiple transitions for even 10ms should give 10^-5 precision. An LC oscillator like the one in https://www.instructables.com/id/bfo-metal-detecto... (left side of the schematic) uses just 1 transistor, 2 capacitors and 1 resistor (plus the coil). There may not even be a need for an external comparator since the Arduino has a built-in comparator, which can be used for interrupts (if I recall well...)OK sorry, just thinking aloud. Could be a project for the ...

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    Time is something that the Arduino can measure with very high precision: it has a pretty stable crystal and the timers can be set up to measure with a resolution of a single clock cycle (1/16th of a microsecond). The length of a single LC pulse won't be very accurate (10^-3 for a single pulse of a 16kHz signal). But keeping track of multiple transitions for even 10ms should give 10^-5 precision. An LC oscillator like the one in https://www.instructables.com/id/bfo-metal-detecto... (left side of the schematic) uses just 1 transistor, 2 capacitors and 1 resistor (plus the coil). There may not even be a need for an external comparator since the Arduino has a built-in comparator, which can be used for interrupts (if I recall well...)OK sorry, just thinking aloud. Could be a project for the christmas holidays! Cheers

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    Hi, I don't think it's possible to go very deep with induction measurement: the magnetic field of a coil diminishes with the 3rd power of the distance/radius. So doubling the depth results in an inductance chance that is 8 times smaller, and very quickly below the detection threshold

    // Metal detector// Runs a pulse over the search loop in series with resistor// Voltage over search loop spikes// Through a diode this charges a capacitor// Value of capacitor after series of pulses is read by ADC// Metal objects near search loop change inductance.// ADC reading depends on inductance.// changes wrt long-running mean are indicated by LEDs// LED1 indicates rise in inductance// LED2 indicates fall in inductance// the flash rate indicates how large the difference is// wiring:// 220Ohm resistor on D2// 10-loop D=10cm seach loop between ground and resistor// diode (-) on pin A0 and (+) on loop-resistor connection// 10nF capacitor between A0 and ground// LED1 in series with 220Ohm resistor on pin 8// LED2 in series with 220Ohm resistor on pin 9// First time, run with with seri...

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    // Metal detector// Runs a pulse over the search loop in series with resistor// Voltage over search loop spikes// Through a diode this charges a capacitor// Value of capacitor after series of pulses is read by ADC// Metal objects near search loop change inductance.// ADC reading depends on inductance.// changes wrt long-running mean are indicated by LEDs// LED1 indicates rise in inductance// LED2 indicates fall in inductance// the flash rate indicates how large the difference is// wiring:// 220Ohm resistor on D2// 10-loop D=10cm seach loop between ground and resistor// diode (-) on pin A0 and (+) on loop-resistor connection// 10nF capacitor between A0 and ground// LED1 in series with 220Ohm resistor on pin 8// LED2 in series with 220Ohm resistor on pin 9// First time, run with with serial print on and tune value of npulse// to get capacitor reading between 200 and 300byte npulse;const byte pin_pulse=A2;const byte pin_cap =A3;const byte pin_LED1 =PB1;const byte pin_LED2 =PB2;const byte pin_tone =PB0;void setup() { pinMode(pin_pulse, OUTPUT); digitalWrite(pin_pulse, LOW); pinMode(pin_cap, INPUT); pinMode(pin_LED1, OUTPUT); digitalWrite(pin_LED1, LOW); pinMode(pin_LED2, OUTPUT); digitalWrite(pin_LED2, LOW); pinMode(pin_tone, OUTPUT); digitalWrite(pin_tone, LOW); //calibrate the number of pulses to apply for (npulse=0; npulse<100; npulse++){ if(meas(npulse)>300)break; } }// perform measurement using n pulsesint meas(byte n){ //reset the capacitor pinMode(pin_cap,OUTPUT); digitalWrite(pin_cap,LOW); delayMicroseconds(20); pinMode(pin_cap,INPUT); //apply the pulses for (byte i=0; i<n; i++){ digitalWrite(pin_pulse,HIGH); //takes 3.5 microseconds delayMicroseconds(3); digitalWrite(pin_pulse,LOW); //takes 3.5 microseconds delayMicroseconds(3); } //read the charge on the capacitor return analogRead(pin_cap); }const byte shortexp=6;const byte longexp=10;long int shortsum=(300<<shortexp);long int longsum=(300<<longexp);long int difsum=0;const int clickval=100;byte ledcnt1=0;byte ledcnt2=0;bool click=false;void loop() { int val=meas(npulse); shortsum+=val; longsum+=val; shortsum-=(shortsum>>shortexp); longsum-=(longsum>>longexp); int dif=shortsum-(longsum>>(longexp-shortexp)); difsum+=dif; click=false; if(difsum>clickval){ ledcnt1=10; click=true; difsum-=clickval; } if(difsum<-clickval){ ledcnt2=10; click=true; difsum+=clickval; } if(click){ if(digitalRead(pin_tone)==LOW)digitalWrite(pin_tone,HIGH); if(digitalRead(pin_tone)==HIGH)digitalWrite(pin_tone,LOW); } if(ledcnt1>0){ digitalWrite(pin_LED1,HIGH); ledcnt1--; } else { digitalWrite(pin_LED1,LOW); } if(ledcnt2>0){ digitalWrite(pin_LED2,HIGH); ledcnt2--; } else { digitalWrite(pin_LED2,LOW); }}

    Thanks for all your feedback Jim and please keep up updated!The method in your link does not look very promising to me.Metal detection by inductance change has severe limitations regarding depth and size of the object. As a rule of thumb, the change in inductance at zero depth corresponds to the area of the object divided by the area of the coil. At nonzero depth, divide that fraction by the 3rd power of the ratio of the distance to the radius. So for a 10cm coil, a 2cm coin at 10cm distance, gives an inductance change of (2/10)**2 / (10/5)**3 = 0.04 / 8 =0.5%.So staying with this technique, the most important is to get good sensitivity to very small changes.The Arduino ADC can easily get to 10^-3, especially with a well-chosen reference and averaging multiple measurements. But 10^-4 wo...

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    Thanks for all your feedback Jim and please keep up updated!The method in your link does not look very promising to me.Metal detection by inductance change has severe limitations regarding depth and size of the object. As a rule of thumb, the change in inductance at zero depth corresponds to the area of the object divided by the area of the coil. At nonzero depth, divide that fraction by the 3rd power of the ratio of the distance to the radius. So for a 10cm coil, a 2cm coin at 10cm distance, gives an inductance change of (2/10)**2 / (10/5)**3 = 0.04 / 8 =0.5%.So staying with this technique, the most important is to get good sensitivity to very small changes.The Arduino ADC can easily get to 10^-3, especially with a well-chosen reference and averaging multiple measurements. But 10^-4 would be hard if not impossible.In fact, the classical BFO metal detector (see e.g. https://www.instructables.com/id/Home-Made-BFO-met... )can be sensitive to 1Hz on a base of 10^5Hz, so 10^-5 sensitivity.I think the following might work: if the coil is made part of an LC circuit (with a good stable capacitor), the Arduino could measure the frequency with very good precision, e.g. by recording time-stamps of the internal timers whenever the oscillating signal goes over threshold (and fires an interrupt). This way the super-high sensitivity of a BFO is achieved, but with much fewer components, and all the flexibility of the Arduino, such as autocalibration, noise filters, and a wide range of output modes.

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    An external reference can indeed also be applied, and would have a similar effect. I would think a resistor-divider would do the job as well. The difference with the internal 1.1V is that Vref from a divider would follow variations in the supply voltage and thus might give better stability...

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  • rgco made the instructable DIY Lab Bench Variable Power Supply 1 year ago
    DIY Lab Bench Variable  Power Supply

    Done! The scheme is the same but a few details differ:For enclosure I used an old plastic nivea handcream pot - it was the first thing I found that seemed to fit the components and it's sturdy enough to fit all dials on the lid yet soft enough to cut the holes without a drill.I left the external PS outside the enclosure and connect it with a DC jack. This way I don't need to cut the cable of the external PS. Unfortunately, the only PS that has a common DC jack, for which I could find cheap female jacks on aliexpress, are 12V. I'm using a 12V 2A PS of an external disk for now.With 12V input the output is limited to ~11V which also means the potentiometers use a very small fraction of the full turn. I'm thinking of adding fixed resistors to the potentiometers to improve their sensitivity,...

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    Done! The scheme is the same but a few details differ:For enclosure I used an old plastic nivea handcream pot - it was the first thing I found that seemed to fit the components and it's sturdy enough to fit all dials on the lid yet soft enough to cut the holes without a drill.I left the external PS outside the enclosure and connect it with a DC jack. This way I don't need to cut the cable of the external PS. Unfortunately, the only PS that has a common DC jack, for which I could find cheap female jacks on aliexpress, are 12V. I'm using a 12V 2A PS of an external disk for now.With 12V input the output is limited to ~11V which also means the potentiometers use a very small fraction of the full turn. I'm thinking of adding fixed resistors to the potentiometers to improve their sensitivity, e.g. adding 10k to the 'useless' leg. Any idea if that'll be OK? It'll behave like a 20k pot, I suppose that's fine but haven't tried it out yet. Ideally I'd replace the 10k potentiometer by a 5k and then add a 5k fixed, but I only have 10K.I really think this PS is the best for everyone on a low budget, the total cost of the components (excluding external PS and enclosure) is about 4 EUR (2 for display, 1 for buck, 1 for pots, switch, jack), and to get a regulated PS with current limit and simultaneous digital readout of voltage and current is awesome. I've already been trying it out on NiCr wire and a Peltier element.My plan is to keep an eye open for a stronger PS and better enclosure and make another one with more power. Cheers!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    Hi, glad you like it!I did read a little about the various types of metal detectors, and I'm afraid that it's hard to improve on this type without fundamental changes. The reason is that this type of metal detection (measuring the inductance) is sensitive to the total inductance of the coil, and it only changes a tiny bit in the vicinity of metals. So you're always looking for a small change on a big number.To overcome that, you need a pulse-induction: send a pulse, then record the response. So you get zero for no metal and something non-zero if there is metal.I think it's possible to make that type with and Arduino as well, but it requires higher voltages, faster switching and better gating. I gave it a quick try but it didn't immediately work and I don't have a fast scope to debug or ...

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    Hi, glad you like it!I did read a little about the various types of metal detectors, and I'm afraid that it's hard to improve on this type without fundamental changes. The reason is that this type of metal detection (measuring the inductance) is sensitive to the total inductance of the coil, and it only changes a tiny bit in the vicinity of metals. So you're always looking for a small change on a big number.To overcome that, you need a pulse-induction: send a pulse, then record the response. So you get zero for no metal and something non-zero if there is metal.I think it's possible to make that type with and Arduino as well, but it requires higher voltages, faster switching and better gating. I gave it a quick try but it didn't immediately work and I don't have a fast scope to debug or study it...

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    Hi!Using the 1.1V reference is a great idea! The sensitivity could increase by up to a factor 5! For the capacitor voltage I had to make a trade-off between large digitisation error at low voltage and low sensitivity to inductance changes at high voltage and so ended up recommending a value of 200-300 (1.0-1.5V). But going in the range 0.8-1.0 V and using the 1.1V reference should solve both problems. Thanks a lot for the idea! I'll definitely try this out for the next version: I'm working on a super-compact version based on the ATTINY13A and using a coincell.Amplifying the difference with an opamp seems a bit of an overkill to me, the component count starts to go up, but in theory what you say should work. A diode with O(1mA) current draw might give a decent reference voltage after wh...

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    Hi!Using the 1.1V reference is a great idea! The sensitivity could increase by up to a factor 5! For the capacitor voltage I had to make a trade-off between large digitisation error at low voltage and low sensitivity to inductance changes at high voltage and so ended up recommending a value of 200-300 (1.0-1.5V). But going in the range 0.8-1.0 V and using the 1.1V reference should solve both problems. Thanks a lot for the idea! I'll definitely try this out for the next version: I'm working on a super-compact version based on the ATTINY13A and using a coincell.Amplifying the difference with an opamp seems a bit of an overkill to me, the component count starts to go up, but in theory what you say should work. A diode with O(1mA) current draw might give a decent reference voltage after which the difference could be multiplied by a factor 10 or so...Thanks for the feedback and the great idea to use the 1.1V reference!

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  • rgco commented on rgco's instructable Simple Arduino Metal Detector1 year ago
    Simple Arduino Metal Detector

    Interesting!If the tube is metal it won't work: it will effectively shield any EM effect inside.If the tube is an isolator it should work easily: a 3cm metal sphere gives a big change in inductance of a 4- or 5 cm coil.Make the diameter of the coils as small as possible and still fit around the tube. That way the change in inductance will be biggest. With some changes to the code, one Arduino should be able to handle 6 coils.Good luck!

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  • rgco followed GreatScottLab1 year ago
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  • rgco commented on MaurizioZ's instructable DIY Lab Bench Variable Power Supply 1 year ago
    DIY Lab Bench Variable  Power Supply

    Right what I need, no-nonsense regulated supply based on old laptop supply. Components ordered, will take a while. You got my vote!

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  • rgco's instructable Thermometer Moodlight's weekly stats: 1 year ago
    • Thermometer Moodlight
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  • rgco followed Kedar Nimbalkar1 year ago
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