Capacitive wireless power transfer question

Started by Anonymous in sci.electronics.design5 years ago 11 replies

Could some electronics guru please shed some light on this ? Consider the following set up. I have an oscillator running at 25 MHz, driving a...

Could some electronics guru please shed some light on this ? Consider the following set up. I have an oscillator running at 25 MHz, driving a 10 pF parallel plate capacitor. The capacitor is made of two single layer copper clad plates of appropriate dimensions, separated by 1.2 mm of FR4. The capacitive reactance at this frequency is about 32 Ohms. What test can I perform to check t...


Pay

Started by Anonymous in sci.electronics.design3 years ago 15 replies

I designed a circuit. It is a PWM thing, four outputs not super high current. Open drain. We got an oscillator, thing to make a triangle wave...

I designed a circuit. It is a PWM thing, four outputs not super high current. Open drain. We got an oscillator, thing to make a triangle wave for the PWM, four comparators for the out put, and no filtering at all and in fact that is EXACTLY what is needed. About 40 components, three dual OP AMPs, four power MOSFETs, the rest elcheapo resistors n shit. I got more time


Me Again, Math Again

Started by Anonymous in sci.electronics.design3 years ago 50 replies

...

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiSvsnY9-_bAhVDja0KHXHnALoQFggpMAA&url=http%3A%2F%2Fphysics.oregonstate.edu%2F~giebultt%2FCOURSES%2Fph412%2FReading%2Foscillators-1p.pdf&usg=AOvVaw2ID2iftO5An0jNHiC1lYRm On page 5 of that they have a phase shift oscillator. I would like to use one in my, well, whatever.


Capacitance value for PIC crystal

Started by P E Schoen in sci.electronics.design8 years ago 41 replies

For most of my projects I use either a 14.7456 MHz crystal (57600*256) = or=20 20.000 MHz (for USB 96 MHz 24*f/5). The 20 MHz crystal I am using...

For most of my projects I use either a 14.7456 MHz crystal (57600*256) = or=20 20.000 MHz (for USB 96 MHz 24*f/5). The 20 MHz crystal I am using = specifies=20 a 20 pF parallel load, but my boards have 12 pF capacitors. I just = noticed=20 this and I think the value had been selected for a previous brand of=20 crystal, but the oscillator frequencies measure pretty close to the = ideal=20 ...


Nightlight problems.

Started by bitrex in sci.electronics.design8 years ago 4 replies

My new nightlight has a cds cell feeding a comparator with a time constant, so it doesn't turn on immediately when the cell is covered. ...

My new nightlight has a cds cell feeding a comparator with a time constant, so it doesn't turn on immediately when the cell is covered. Only problem is that if you put it too close to something, you get a relaxation oscillator: http://youtu.be/er44GoUs5Wc -- ----Android NewsGroup Reader---- http://www.piaohong.tk/newsgroup


Ultra high frequency oscillators

Started by Anonymous in sci.electronics.design5 years ago 21 replies

Could some electronics guru please shed some light on this ? How is the carrier wave for high frequency wireless communication transmitters...

Could some electronics guru please shed some light on this ? How is the carrier wave for high frequency wireless communication transmitters generated ? Specifically, any oscillator would need negative impedance device, e.g., a bipolar transistor to sustain the oscillations. So, what transistors would be used in e.g., a GSM transmitter with a carrier frequency of 1.8 GHz Thanks in ...


single transistor oscillator

Started by Vivek N in sci.electronics.design8 years ago 11 replies

I tried building a single transistor LED flasher like this...

I tried building a single transistor LED flasher like this : http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html I didn't have the recommended 2n2222 - I tried with a BC548, 2n2369 and 2n3055 - None of them work. I'm using a trimpot set to 2 kiloohms and a 470 microfarad capacitor. Instead of a 100 ohm resistor I put 3 superbright LEDs in series. I get 1.2 v...


4kHz piezo transmitter in 5 minutes

Started by Jan Panteltje in sci.electronics.design8 years ago 1 reply

Tried to find the circuit diagram of my old Doppler ultrasonic radar experiments, not found. Had to have the parts somewhere, BINGO. No idea...

Tried to find the circuit diagram of my old Doppler ultrasonic radar experiments, not found. Had to have the parts somewhere, BINGO. No idea how to connect that old coil from a Philips acoustic remote (transducers are from remotes too), Measured inductances, see circuit diagram on paper in background, build a simple 1 transistor oscillator with most likely connections, worked first time: ht...


Running out of ideas: stability, bootstrap

Started by Gerhard Hoffmann in sci.electronics.design5 years ago 24 replies

Hi, all, we had a bank holiday here, nicely positioned close to the weekend and I took the free time to play with my multi-IF3601 low noise...

Hi, all, we had a bank holiday here, nicely positioned close to the weekend and I took the free time to play with my multi-IF3601 low noise amplifier. That was not so funny because it features a negative input impedance over most frequencies, so with a suitable inductance on the input it makes a stable oscillator. Some observations: - Zin is negative also with the feedback loop cu...


Has any one tried this..

Started by Maynard A. Philbrook Jr. in sci.electronics.design7 years ago 12 replies

Making a small hand tool and want to condense part count to min.. I need a +/- 5 volt rail, also I need a fast running +/- square pulse and the...

Making a small hand tool and want to condense part count to min.. I need a +/- 5 volt rail, also I need a fast running +/- square pulse and the inverter section at the collector of Q1 supplies +/- 5 volts, which is perfect. I take one op-amp out of four and made the standard relaxation oscillator for the square wave, ~20Khz. it starts off with 0 volts at the Vee but the inverter will bring...


Low component count relaxation oscillator

Started by Syd Rumpo in sci.electronics.design6 years ago 28 replies

I have a cheap torch (US: flashlight) which has three AAA cells in series powering nine white LEDs in parallel, nothing else that I can see. ...

I have a cheap torch (US: flashlight) which has three AAA cells in series powering nine white LEDs in parallel, nothing else that I can see. I guess the current is limited by the battery impedance. One LED is off, four are on, three flashing at about 15Hz and one flashes every few seconds. I suppose when on, the current draw is sufficient to drop the battery voltage, the three LEDs...


How yo detect capacitive power coupling

Started by Anonymous in sci.electronics.design6 years ago 8 replies

Could some electronics guru please help ? Suppose a high frequency(approx. 30 - 40 Mhz) oscillator connected across a aimple 1 cm x 1 cm plate...

Could some electronics guru please help ? Suppose a high frequency(approx. 30 - 40 Mhz) oscillator connected across a aimple 1 cm x 1 cm plate area parallel plate capacitor, with a 1 mm thick dielectric plate in between, material FR4. Now how do I detect that indeed the signals are being transmitted between the plates, given that a capacitor is a short to AC. Also, if I connect a sim...


[?] PIC16F628A - are all I/O ports tri-stated when chip is reset.

Started by David Chapman in sci.electronics.design10 years ago 5 replies

Greetings, I wish to use two PIC16F628A processors in a particular circuit I'm putting together. They will each have a different clock...

Greetings, I wish to use two PIC16F628A processors in a particular circuit I'm putting together. They will each have a different clock oscillator frequency, and only one PIC will ever need to operate at any particular time. Some of the I/O lines in the circuit are common to both processors so I'd like to ask the PIC experts in this NG if, when held in the Reset condition, it...


Solar garden light schematic.

Started by Ian Field in sci.electronics.design8 years ago 2 replies

On A.B.S.E I've posted the schematic of a solar Led garden light in the hope someone can name the type of oscillator. Thanks.

On A.B.S.E I've posted the schematic of a solar Led garden light in the hope someone can name the type of oscillator. Thanks.


Novel Zeitgeber devive for antique clock

Started by Anonymous in sci.electronics.design8 years ago 48 replies

I have an antique clock which I have retrofitted with an oscillator circuit= to make it very accurate. I did not use a sensor, nor did I modify...

I have an antique clock which I have retrofitted with an oscillator circuit= to make it very accurate. I did not use a sensor, nor did I modify the clo= ck's mechanism or its iron pendulum bob in any way. There is absolutely no = circuit or sensor which measures the clock. Yet it works. How did I do it? Any ideas? (I think it's novel, but it is so obvious, I am open to hearing differentl...


LTSpice: How do make a Schmitt oscillator run?

Started by Joerg in sci.electronics.design13 years ago 8 replies

Ok, simple circuit: Schmitt inverter, 10K resistor from output to input, 1000pF capacitor from input to ground. Vh set to about 20% of Vhigh....

Ok, simple circuit: Schmitt inverter, 10K resistor from output to input, 1000pF capacitor from input to ground. Vh set to about 20% of Vhigh. Should happily oscillate but I get the error message "Time step too small". Also there is a noted dip in voltage down to about 80%, something which should even be possible with a digital behavioral device. What gives? How can I fix that and make i...


Low Jitter 20MHz oscillator

Started by hbv in sci.electronics.design9 years ago 49 replies

Hi all, We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single ended ), 20Mhz (+-few percent...) and most important a low...

Hi all, We need a low jitter clock generator ( 3v3 or 1v8 CMOS output single ended ), 20Mhz (+-few percent...) and most important a low jitter on this output (few ps). Any ideas are welcomed. Habib.


unijunction equivalent circuit?

Started by Joseph H Allen in sci.electronics.design8 years ago 5 replies

So is there any simple circuit using conventional NPN and PNP transistors? I've seen this...

So is there any simple circuit using conventional NPN and PNP transistors? I've seen this circuit http://sub.allaboutcircuits.com/images/quiz/02139x02.png in _Sourcebook of Electronic Circuits_, but it doesn't really work- it latches but does not release when used in a relaxation oscillator. Perhaps it did work with lower gain transistors. -- /* jhallen@world.std.com AB1GO */ ...


44kHz radar time of flight, yes and no

Started by Jan Panteltje in sci.electronics.design8 years ago 6 replies

http://youtu.be/dnrH-7DyGXI This works, increasing the distance between transmitter and receiver increases the delay of the received...

http://youtu.be/dnrH-7DyGXI This works, increasing the distance between transmitter and receiver increases the delay of the received signal. I used a Raspberry Pi to make the on/off pulse, well of course some 555 timers could do it too. A small 2 transistor switch keys the transmitter oscillator driven from a GPIO pin. Youtube resolution is a bit low to see the scope, top trace is tr...


My current mirror variation on the Baxandall Class-D oscillator - minor revisons

Started by Bill Sloman in sci.electronics.design1 year ago

I've changed the circuit a bit - essentially taking out bits that didn't add value - but I did change the Sallens and Keys filter to one with a...

I've changed the circuit a bit - essentially taking out bits that didn't add value - but I did change the Sallens and Keys filter to one with a bit of gain that gives you a maximally flat time delay with standard value components. The performance is marginally better. http://sophia-electronica.com/BillsBaxandall.html -- Bill Sloman, Sydney