Type: Posts; User: BradtheRad

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  1. 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.
  2. 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...
  3. 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...
  4. Replies

    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.


    This won't make up indefinitely for sagging...
  5. 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.

  6. 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...
  7. 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...
  8. 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...
  9. 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...
  10. 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.
  11. 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...
  12. Replies

    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.
  13. 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.
  14. Replies

    Closed: Re: Bridge diode thermal problem

    With load absent, an unregulated supply tends to rise to the maximum amplitude coming from the transformer. This is true whether filtering is choke type or capacitor type.

    You must install a...
  15. Closed: Re: Tools to detect AC electric leakage/loss in home electricity

    You can measure current draw of some appliances, but other appliances have an On-Off cycle. Those could use some kind of time-logging device.

    I tracked my refrigerator cycles with my VIC-20...
  16. Replies

    Closed: Re: Bridge diode thermal problem

    Capacitive filtering draws short bursts of current. To get 5A output you must supply bursts of current on the order of 30A to 60 A. I*I*R losses are high. Heating effect is high, through diodes and...
  17. Replies

    Closed: Re: High Speed Motion Sensor of Object


    * Do you wish to detect if the pitch is in a strike zone directly above the plate (about 12 inches wide)?

    * Is a bat or batter's arm in the field of view of an optical sensor?

    - -...
  18. Replies

    Closed: Re: "Self-Healing" 12V 30A Circuit

    An article about self-healing circuits suggests it's for complex systems with sensors that detect a problem growing, and re-route or shut down affected paths in time to avoid catastrophic failure.
  19. Replies

    Closed: Re: Question about RF power meter

    The grid dip meter is a useful instrument for radio enthusiasts. It's popular because it's possible to build your own from a few discrete components.

    With a filter you can stop it from responding...
  20. Closed: Re: Extracting energy from gyroscope precession

    I believe your observation which demonstrates that moving the center of gravity starts a swinging motion. The apparatus must obey the force of gravity so its greatest mass is closest to earth.
  21. Closed: Re: How to get two Sweep and Repeat Generators in sync.

    Many types of oscillators change frequency if you change supply voltage. Or you can 'bend' an RC time constant by changing a resistance somewhere in the circuit, or by applying a voltage at a...
  22. Closed: Re: Mains voltage logger could do with more resolution

    Is your setup an expanded-scale meter? It's made by installing a zener diode inline with the voltage you're measuring. Select a value so 180V yields a reading just above the zeroline. Then condense...
  23. Replies

    Closed: Re: Decoupling Capacitance in IC Layo

    Make the Farad value sufficient so the DC voltage does not change too much from cycle to cycle. 5 or 10 percent ripple is easily noticed on an oscilloscope therefore it seems like a reasonable goal....
  24. Replies

    Closed: Re: BLDC motor delta winding

    Is your scope dual channel? The obvious (and direct) hookup is to ground the scope at one node of the delta, and probe the other two nodes. The scope ought to have an isolated power supply.

    As an...
  25. Closed: Re: Mains leaking currents causing problems in my house

    Here in the US, house wiring once had 2 wires only. I saw appliances that gave me a shock if I touched them and a metal faucet simultaneously. Or if I was barefoot on wet ground.

    The shock stopped...
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