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Type: Posts; User: betwixt

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1. ## Thread: Tracking Phase comparator Logic

by betwixt
Replies
10
Views
154

### Closed: Re: Tracking Phase comparator Logic

If 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 difference. What you need to do is count at 5uS rate...
2. ## Thread: MOC3020/BTA41 circuit problem

by betwixt
Replies
10
Views
280

### Closed: Re: MOC3020/BTA41 circuit problem

Hasan, 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 means I was right about not having enough current...
3. ## Thread: MOC3020/BTA41 circuit problem

by betwixt
Replies
10
Views
280

### Closed: Re: MOC3020/BTA41 circuit problem

I 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 handle a low voltage. The maximum voltage it can...
4. ## Thread: MOC3020/BTA41 circuit problem

by betwixt
Replies
10
Views
280

### Closed: Re: MOC3020/BTA41 circuit problem

Note the different resistor arrangement around the triac! The Chinese design uses a capacitor to filter noise from the gate and to partially snub spikes from across the line. For driving a heater...
5. ## Thread: MOC3020/BTA41 circuit problem

by betwixt
Replies
10
Views
280

### Closed: Re: MOC3020/BTA41 circuit problem

Two 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 suggest a value of 2.2K or higher. Remember that...

by betwixt
Replies
1
Views
275

### Closed: Re: Metal detector with Arduino ADC channel.

It 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 magnetic field, either by absorbing or de-tuning...
7. ## Thread: [PIC] Car Cooling System PSU Design Related

by betwixt
Replies
15
Views
536

### Closed: Re: [PIC] Car Cooling System PSU Design Related

Does 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 time but you will not be able to use the '24v'...
8. ## Thread: [PIC] Car Cooling System PSU Design Related

by betwixt
Replies
15
Views
536

### Closed: Re: [PIC] Car Cooling System PSU Design Related

There 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 they are in series, you need >24V to do that.
If...
9. ## Thread: [PIC] Car Cooling System PSU Design Related

by betwixt
Replies
15
Views
536

### Closed: Re: [PIC] Car Cooling System PSU Design Related

Doesn'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 step down the PV voltage so it can charge the...
10. ## Thread: problem with coding 123

by betwixt
Replies
8
Views
373

### [SOLVED]Closed: Re: problem with coding 123

I 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 still 10 bits.
Some Arduino device can use 12-bit...
11. ## Thread: problem with coding 123

by betwixt
Replies
8
Views
373

### [SOLVED]Closed: Re: problem with coding 123

... 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 the precision isn't increased to 12-bits.

Brian.

by betwixt
Replies
13
Views
509

### Closed: Re: MAR8 prior to AD8307

Yes, 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 follow that route is to amplify the lower voltage...

by betwixt
Replies
13
Views
509

### Closed: Re: MAR8 prior to AD8307

If 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 provision for a filter capacitor at one of the pins...

by betwixt
Replies
13
Views
509

### Closed: Re: MAR8 prior to AD8307

It 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 adjust calibration accurately or apply a voltage...

by betwixt
Replies
13
Views
509

### Closed: Re: MAR8 prior to AD8307

If you use a 100uA meter you can probably drive it directly from the AD83xx.

Brian.
16. ## Thread: How to create a voltage selector circuit

by betwixt
Replies
6
Views
319

### Closed: Re: How to create a voltage selector circuit

I 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 'bar graph' output with none, lowest, lowest and...
17. ## Thread: VU Meter only with 1LED (PWM) no IC except for OPAMP

by betwixt
Replies
6
Views
279

### Closed: Re: VU Meter only with 1LED (PWM) no IC except for OPAMP

You 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 flash at the frequency of the audio instead of its...
18. ## Thread: VU Meter only with 1LED (PWM) no IC except for OPAMP

by betwixt
Replies
6
Views
279

### Closed: Re: VU Meter only with 1LED (PWM) no IC except for OPAMP

Not 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 level proportional to the sound level. Then you...
19. ## Thread: Simple 50R I/O RF attenuator (1-30MHz)

by betwixt
Replies
14
Views
478

### Closed: Re: Simple 50R I/O RF attenuator (1-30MHz)

Just 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 matching but you might get something close enough if you...
20. ## Thread: Rectifier diodes with bypass capīs & gounding speaker basketīs

by betwixt
Replies
33
Views
1,348

### Closed: Re: Rectifier diodes with bypass capīs & gounding speaker basketīs

Based on what we have already said, Carbon dioxide resistors would be best but you might have trouble soldering to them. :)

Really, the snubber circuits are not going to make one iota of...
21. ## Thread: ACS710 - pin 1 to 8 is shorted all together

by betwixt
Replies
2
Views
235

### Closed: Re: ACS710 - pin 1 to 8 is shorted all together

They are internally connected together through a copper loop so they should measure as shorted.
The load current (or a proportion of it) passes through those pins and the internal circuits measure...
22. ## Thread: Inrush current limiter

by betwixt
Replies
7
Views
379

### Closed: Re: Inrush current limiter

A 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 across it. The inductor will slow the current rise and...
23. ## Thread: specific use of volatile keyword

by betwixt
Replies
2
Views
217

### Closed: Re: specific use of volatile keyword

Volatile 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 counting 'x' upwards and your ISR changed the value...
24. ## Thread: Inrush current limiter

by betwixt
Replies
7
Views
379

### Closed: Re: Inrush current limiter

Most 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 charge current to a capacitor but if the load is...
25. ## Thread: Inrush current limiter

by betwixt
Replies
7
Views
379

### Closed: Re: Inrush current limiter

... and your thermistor tries to drop 2.5 * 10 = 25V as well.

First explain what you mean by "it produces sparks" as this is nothing to do with inrush current.

Brian.
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