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Type: Posts; User: BradtheRad

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1. ## Thread: Capacitive Boost or Charge-Pump DC-DC Converter

by BradtheRad
Replies
1
Views
62

### Closed: Re: Capacitive Boost or Charge-Pump DC-DC Converter

Diagrams of the Dickson frequently have two clocks driving it. These are in fact a full H-bridge which turns the DC supply into AC applied to the network. The circuit becomes similar to a half-wave...
2. ## Thread: Ultrasonic transducer driver

by BradtheRad
Replies
5
Views
408

### Closed: Re: Ultrasonic transducer driver

This driver starts with a square-wave oscillator. Frequency is adjustable. (It does not auto-detect resonant frequency.) You must find a frequency which gets best response from the transducer.

A...
3. ## Thread: Ultrasonic transducer driver

by BradtheRad
Replies
5
Views
408

### Closed: Re: Ultrasonic transducer driver

My schematic illustrates a concept of operation, an automatic method to detect resonant frequency. Where I have a series LC, there needs to be the correct model for your transducer.

Or instead...
4. ## Thread: Calculate Capacitance Value from Smith Chart

by BradtheRad
Replies
24
Views
1,167

### [SOLVED]Closed: Re: Calculate Capacitance Value from Smith Chart

And yes, I pointed out that formula entering the picture in my post #17. So let's see if things are clearing up. I compared more variations to see what happens.

At left, equal voltages appear...
5. ## Thread: Calculate Capacitance Value from Smith Chart

by BradtheRad
Replies
24
Views
1,167

### [SOLVED]Closed: Re: Calculate Capacitance Value from Smith Chart

Even if I were experienced at calculations with imaginary numbers and complex impedances, it's obvious I would need to learn more in order to account for the results of my Wheatstone bridge...
6. ## Thread: Calculate Capacitance Value from Smith Chart

by BradtheRad
Replies
24
Views
1,167

### [SOLVED]Closed: Re: Calculate Capacitance Value from Smith Chart

Yes, it would all be simpler if I'd seen only the calculator at the 'allaboutcircuits.com' webpage (post #2).
1/(2 ∏ f C)
The XC formula would be sufficient and I'd be happy to leave it at that.
...
7. ## Thread: Phase current motor measurements with cro

by BradtheRad
Replies
2
Views
220

### Closed: Re: Phase current motor measurements with cro

Is this question the same as in your recent link below? Did you try suggested methods?

"BLDC motor delta winding"

https://www.edaboard.com/showthread.php?386841
8. ## Thread: Calculate Capacitance Value from Smith Chart

by BradtheRad
Replies
24
Views
1,167

### [SOLVED]Closed: Re: Calculate Capacitance Value from Smith Chart

Here's the second half of my simulation. I increased ohmic resistance to 77 ohms, to see if
capacitive impedance still indicates 77 ohms according to the raw XC formula.

We expect it should...
9. ## Thread: Ultrasonic transducer driver

by BradtheRad
Replies
5
Views
408

### Closed: Re: Ultrasonic transducer driver

A full H-bridge is the convenient method to create AC from a single DC supply. It's a variation of the astable multivibrator.

You can adjust values so large supply current goes through a load.
...
10. ## Thread: Wiring of DC fans in Series

by BradtheRad
Replies
20
Views
930

### [SOLVED]Closed: Re: Wiring of DC fans in Series

Call this a 'quasi' buck converter, balancing voltage to two dissimilar loads in series. (Without it the loads receive 22.5V top, 7.5V bottom.)

156087

Supplemental current is added to the...
11. ## Thread: Calculate Capacitance Value from Smith Chart

by BradtheRad
Replies
24
Views
1,167

### [SOLVED]Closed: Re: Calculate Capacitance Value from Smith Chart

When there is negligible ohmic resistance, it's true that the capacitive reactance formula tells the impedance.

156079

However if the resistor value is increased, it changes the situation so...
12. ## Thread: Battery cutoff voltage vs 0% battery voltage

by BradtheRad
Replies
5
Views
334

### Closed: Re: Battery cutoff voltage vs 0% battery voltage

One thing to consider is whether your device does something bad in the event that supply voltage drops to 3V? Example, loss of data in memory?

Do you want an alert to appear so you can do one more...
13. ## Thread: Calculate Capacitance Value from Smith Chart

by BradtheRad
Replies
24
Views
1,167

### [SOLVED]Closed: Re: Calculate Capacitance Value from Smith Chart

Not in all cases. There is a difference due to a phase change. The calculation needs to be fine-tuned by drawing parallelogram angles as shown in textbooks.
14. ## Thread: Generation of 4 Phase Shifted clock Signals

by BradtheRad
Replies
12
Views
651

### [SOLVED]Closed: Re: Generation of 4 Phase Shifted clock Signals

4-stage chaser (sequencer) made with transistors. It's an extension of a 3-stage chaser whose principle is similar to the classic 2-transistor astable multivibrator. One led at a time is lit, moving...
15. ## Thread: Zener diode simulation problem using multisim 12.0

by BradtheRad
Replies
5
Views
291

### Closed: Re: Zener diode simulation problem using multisim 12.0

Did you try a similar circuit from the examples folder?

Did the same problem appear with simpler circuits? Say, a resistor and voltage source?

Once you get a simple circuit to work, then add...
16. ## Thread: Maintaining supply voltage on load

by BradtheRad
Replies
3
Views
234

### Closed: Re: Maintaining supply voltage on load

For an easy thing to try, install a resistor to isolate the sensitive device from the noisy supply. Add a reservoir capacitor as shown below.

156044

This won't make up indefinitely for sagging...
17. ## Thread: Regulator strategy - embedded system power design

by BradtheRad
Replies
3
Views
335

### Closed: Re: Regulator strategy - embedded system power design

You're probably interested in a switching power regulator. A buck converter can give efficient performance. If you really want to obtain 3.8V from 3V, then a buck-boost is a suitable option.

A...
18. ## Thread: Desperate for help (computer fan control) or this could cost huge \$\$\$

by BradtheRad
Replies
7
Views
530

### Closed: Re: Desperate for help (computer fan control) or this could cost huge \$\$\$

To know what's going on you must monitor several readings. You need to know what volt levels go to the fan. You must confirm temperature of the device (or more than one device) that causes the fan to...
19. ## Thread: Can IP(Intellectual Property) open source, what does good business model?

by BradtheRad
Replies
6
Views
706

### Closed: Re: Can IP(Intellectual Property) open source, what does good business model?

Not that I speak from business know-how, but I have a hunch that a programmer who demonstrates excellence (without pay) in view of the community, receives an invitation of some kind to make money...
20. ## Thread: Magnetic flux conduit for flux concentration?

by BradtheRad
Replies
21
Views
4,626

### Closed: Re: Magnetic flux conduit for flux concentration?

This topic is interesting however eddy currents are invisible and tend to do the unexpected. I'm still trying to get my mind around the way a neodymium magnet defies gravity, slowing down as it falls...
21. ## Thread: Simple question on Transresistance Amplifier circuit

by BradtheRad
Replies
5
Views
398

### Closed: Re: Simple question on Transresistance Amplifier circuit

In some cases you may wish to apply some amount of bias to your photodetector, to bring it to a threshold where it responds reliably to a trigger event. The goal is to adjust your circuit to a 'good...
22. ## Thread: multiple channel "DC OK" signal ANDing with galvanic isolation

by BradtheRad
Replies
2
Views
398

### Closed: Re: multiple channel "DC OK" signal ANDing with galvanic isolation

Diode logic can be used as long as your range of voltage is such that one low vote affects the resultant signal causing it to be pulled low.
It can be done with 10 diodes and one pullup resistor.
23. ## Thread: Algorithm to estimate given battery chemistry and capacity

by BradtheRad
Replies
3
Views
339

### Closed: Re: Algorithm to estimate given battery chemistry and capacity

I have not heard of a smart charger which is able to detect Amp-hour capacity of a random cell.

It's a bad idea to charge a cell unless you know how well it tolerates mistakes. You ought to know...
24. ## Thread: Impedance Calculation

by BradtheRad
Replies
5
Views
514

### Closed: Re: Impedance Calculation

Vout is a percentage of Vin. The formula is:

(4700 + Z)
divided by
(50M + 4700 + Z)

To find Z, make the above formula equal to your desired percentage, then solve for Z algebraically.
25. ## Thread: Tools to detect AC electric leakage/loss in home electricity

by BradtheRad
Replies
6
Views
785

### Closed: Re: Tools to detect AC electric leakage/loss in home electricity

There are sensitive meters which detect live wires behind walls. Sold as '3-in-1' wall scanners. Inexpensive ones cost \$13-20.
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