betwixt
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Yesterday, 21:12betwixt replied to a thread Sensitive metal detector using microcontroller ADC channel. in MicrocontrollersNot a 555, that would be a bad choice. A comparator would be best with a schmitt trigger logic gate next best. If the Arduino has a schmitt trigger...8 replies | 776 view(s)
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Yesterday, 10:14betwixt replied to a thread Basic 12v Battery VOLTAGE METER, more resolution needed in Elementary Electronic QuestionsIts a long time since I used an LM3914 but I think it's possible to lift the bottom of the divider chain above ground to set the minimum reading. The...7 replies | 303 view(s)
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Yesterday, 10:00betwixt replied to a thread White residue after solder mask develope!!! in Miscellaneous EngineeringI think they mean the uneven surface after plating, you can just see it against the gold. I suspect this is the underlying copper being uneven and...3 replies | 178 view(s)
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13th December 2019, 10:29betwixt replied to a thread Sensitive metal detector using microcontroller ADC channel. in MicrocontrollersThat is the correct type of coil but the inductance depends upon how you use it. In its simplest form, you use the inductance and a small capacitance...8 replies | 776 view(s)
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11th December 2019, 10:19If I understand the requirement and it has to be done digitally, an XOR function of the two signals will produce a high during the time phase...12 replies | 449 view(s)
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11th December 2019, 10:12betwixt replied to a thread MOC3020/BTA41 circuit problem in Hobby Circuits and Small Projects ProblemsHasan, please start a new thread with your questions as these are not the same as the ones Abuhafss is posting. If shorting LED1 makes it work it...10 replies | 439 view(s)
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11th December 2019, 00:05betwixt replied to a thread MOC3020/BTA41 circuit problem in Hobby Circuits and Small Projects ProblemsI If the bridge rectifier is directly across the AC it has to bear the full AC voltage, if you place the resistor before the bridge it only has to...10 replies | 439 view(s)
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10th December 2019, 21:56betwixt replied to a thread MOC3020/BTA41 circuit problem in Hobby Circuits and Small Projects ProblemsNote the different resistor arrangement around the triac! The Chinese design uses a capacitor to filter noise from the gate and to partially snub...10 replies | 439 view(s)
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10th December 2019, 17:02betwixt replied to a thread MOC3020/BTA41 circuit problem in Hobby Circuits and Small Projects ProblemsTwo points: R4 value looks too low, it is only there to ensure the gate has some leakage current when the output of the MOC3020 is high impedance, I...10 replies | 439 view(s)
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10th December 2019, 09:56betwixt replied to a thread Sensitive metal detector using microcontroller ADC channel. in MicrocontrollersIt might work as a strong magnet detector but never as a sensitive metal detector! Metal detectors work by measuring the effect the metal has on a...8 replies | 776 view(s)
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8th December 2019, 14:29Does your application permit charging one battery at a time? With some MCU intervention and some current steering it is possible to charge one at a...24 replies | 868 view(s)
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8th December 2019, 12:49There is a clue in the MOSFET symbol about that! I can't understand why you need the 15V. If it is to charge the batteries you can't do it while...24 replies | 868 view(s)
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8th December 2019, 12:05Doesn't look at all right to me. I'm not sure what any of the circuit really does. D2 seems to have no purpose at all. If the DC-DC converter is to...24 replies | 868 view(s)
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6th December 2019, 17:09I understand that Klaus but it doesn't increase 10 bits to 12 bits, it just multiplies the result by 4, the LSB will always be zero. The ADC is...8 replies | 487 view(s)
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6th December 2019, 14:58... and what is the point in multiplying the result by 4? It is still a 10-bit value with zeroes at the end. It may be stored with extra bits but...8 replies | 487 view(s)
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6th December 2019, 09:47Yes, but with the risk of damaging the meter and possibly the IC at higher signal levels. It isn't a safe strategy. A better approach if you want to...13 replies | 562 view(s)
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5th December 2019, 21:55If you add a capacitor at the output of the internal amplifier it may go unstable. Check the data sheet for the AD83xx device you choose, there is...13 replies | 562 view(s)
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5th December 2019, 20:32It has a built in voltage amplifier so all you have to do is add a series potentiometer to limit the meter current. You would need a reference to...13 replies | 562 view(s)
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5th December 2019, 17:13If you use a 100uA meter you can probably drive it directly from the AD83xx. Brian.13 replies | 562 view(s)
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5th December 2019, 09:53betwixt replied to a thread How to create a voltage selector circuit in Hobby Circuits and Small Projects ProblemsI thnk a better topology is to feed your voltage to all the comparators in parallel but set a different threshold for each one. The will give you a...6 replies | 347 view(s)
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4th December 2019, 16:29betwixt replied to a thread VU Meter only with 1LED (PWM) no IC except for OPAMP in Hobby Circuits and Small Projects ProblemsYou can't use the outputs of comparators directly because all you get is an on/off indication of the instantaneous level. You would see the output...6 replies | 308 view(s)
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2nd December 2019, 17:05betwixt replied to a thread VU Meter only with 1LED (PWM) no IC except for OPAMP in Hobby Circuits and Small Projects ProblemsNot PWM, what you need is an op-amp as a gain stage, a rectifier (either diode or better still an op-amp based precision rectifier) to give you a DC...6 replies | 308 view(s)
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2nd December 2019, 16:56betwixt replied to a thread Simple 50R I/O RF attenuator (1-30MHz) in RF, Microwave, Antennas and OpticsJust a thought - it is possible to use pre-set potentiometers with plastic center 'screws', either a slot or hex hole? You won't get perfect...14 replies | 547 view(s)
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1st December 2019, 19:48betwixt replied to a thread Rectifier diodes with bypass capīs & gounding speaker basketīs in Hobby Circuits and Small Projects ProblemsBased on what we have already said, Carbon dioxide resistors would be best but you might have trouble soldering to them. :) Really, the snubber...33 replies | 1423 view(s)
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30th November 2019, 09:59They are internally connected together through a copper loop so they should measure as shorted. The load current (or a proportion of it) passes...2 replies | 251 view(s)
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29th November 2019, 16:30A cheaper alternative might be a low-Q inductance in series with the incoming power. Something like a 50 - 100uH choke with a ~22 Ohm resistor...7 replies | 431 view(s)
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29th November 2019, 16:26Volatile would be a hint to the compiler to re-read the variable because it could have been changed by the ISR. For example, if your main code was...2 replies | 236 view(s)
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29th November 2019, 11:46Most components are rated to handle higher current for brief periods so I doubt any damage would occur in any case. There are methods to limit the...7 replies | 431 view(s)
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