Search Engine www.edaboard.com

285 Threads found on edaboard.com: Oscillating
I can imagine many circuits belonging to this category, e.g. self oscillating inductive voltage converters. I guess, the battery suggest an efficient converter and this will be most likely a modern integrated boost converter with low quiescent current and voltage regulation.
You have already answered the question yourself by referring to LTC3108 in another thread, I think. Generally speaking, a self oscillating transformer voltage converter based on depletion mode transistors is the way to go. This can be possibly a simple one transistor circuit, but efficiency won't be as good as with LTC3108.
An electronic oscillator is an electronic circuit that produces a repetitive, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current signal. They are widely used in many electronic devices. Common examples of signals generated by oscillators include si
I put the circuit in a simulator and it works. T1 is oscillating, is amplifying, is doing the job mentioned. T1 it is a Colpitts oscillator, C2 (the one between emitter and collector) is one of the feedback capacitors, and BE internal capacitance of the transistor is the second feedback capacitor. Because the BE capacitance is small, the circuit
I'll contradict the somewhat general claim in the post title. There are two problems involved with the original circuit: - it's not oscillating with an 1:1:1 transformer because the load impedance is cancelling the positive feedback action. 1:1:0.5 (in terms of inductance) will already work. - after changing the transformer ratio or increasing
Hi! ALL: Can anyone tell why the CCO circuit in the web address below is not oscillating?Please help!:|
EL panels appear as capacitors to the inverter. The panel with larger area will have larger capacitance. Either the inverter simply isn't able to produce enough voltage with the bigger load or, if it's a self oscillating inverter, the capacitance has stopped it oscillating altogether. Brian.
Hello, Below is the current source ckt for thermistor( RL). 78476 I am using the current source(approx 0.1mA) to excite the thermistor(RL). RL = 100 Ohm .When I check (+) terminal of opamp with oscilloscope ,the waveform found oscillating (Saw tooth like waveform, mean value 2.5V DC but pk value 4.0V ). What causes
first things I would check are: 1) is the fet adequately heat sunk? 2) is there a chance the fet is oscillating at low frequency (like 10 MHz) and wiping itself out. Did you do a wideband stability analysis. I see a lot of funky things designed into LDMOS bias networks to kill low frequency oscillations.
Hi, We have recently moved our design onto a PCB but have encountered problems with what looks to be noise on a switching signals from one IC, the IC is a 125kHz antenna driver for a RFID application. On a prototype board the 125kHz square wave is clean (see picture left) but when on the PCB the signal has a decaying oscillation after each switc
There are oscillators that do have subharmonics. They are the Push-Push type of devices with two transistors. For example, each transistor is oscillating at 1 GHz, but because of the phasing of the Push-Push output structure, it looks like they are oscillating at 2 GHz. There would be a lot of 1 Ghz leakage though. DDS's have harmonics as wel
I would guess the inductor stops unwanted modes of oscillation from happening, like if it was a 3rd order crystal the L-C keeps if from oscillating at the 1st order frequency. The 0.01 uF is just a DC block to keep the Xtal IN from shorting out to ground. 22 pF in parallel with 470 nH implies the desired frequency of oscillation is around 50 MH
I have to wonder if it has to do with the fact that you have two voltage feedback loops, which isn't normal in a flyback converter. Can you verify whether just one or both optocouplers are conducting when the oscillation happens? Also what is the frequency of the oscillation? When oscillating, does the converter operate in DCM or CCM? It migh
I think that your PA is oscillating, because is built on a breadboard with nor real RF grounding.
Hi all, I have designed a sigma-delta ADC in matlab and in cadence. In matlab/simulink it works fine and it is tolerant to ?15% variation in parameters, but in cadence in ss-corner it oscillates (even post layout simulation for the other corners are working fine), the AC analysis for ss-corner and other corners are almost the same(it might be on
Self oscillating 25W CFL Lamp Circuit
Hello, I wish to add slope compensation to a self oscillating boost converter, it is 12V input and Vout = 90V (its 36 amber leds in series at I = 30mA). The circuit inductor squeals like mad, and i wish to add slope compensation, -there is no oscillator, so i suppose i have to couple the drain volage back to the source current sense as a kind
Check the output with CRO. The output voltage may be steady 4% dropped or may be oscillating with a ripple peak to peak 8%. If the output is steady 4% dropped then you have to increase the gain of error amp. If the output is oscillating then you have to reduce the gain of the error amp.
The relay needs to have a certain current through the coil in order for the contacts to energize. If the current falls to a low value, the relay opens. Fluctuating... Do you mean it's oscillating? Does the supply voltage drop when the relay switches on the load? This might result in the relay opening unintentionally. Then the supply voltage r
Hi , I am designing an LC VCO ... So I need a varactor ... when I connect the varactors RIGHT, I mean the positive terminals to oscillating nets and the -ve terminal to ground, the oscillating frequency does not vary with varying control voltage ... So, I folded the varactors, it worked ! ... But with -ve Kvco , increasing control voltage leads t
That’s a Royer converter, this circuit is an auto-oscillating resonant using two transistors in push-pull configuration to provide a symmetrical more details read here:
It sounds as though your circuit is unstable and oscillating at some unknown frequency. So make sure there is shielding between stages and adequate Vcc line decoupling. To de-bug it try putting a 10K resistor right on the end of your live DVM lead. Measure the DC voltage on the oscillator base, then put your finger across the crystal - t
The TLC271 is a low power op amp. It does not like your 0.2 or 0.5uF capacitor as a load. It's oscillating. Either make R's 10-20 times larger and C's 10-20 times smaller, or depending on how much attenuation you actually need, just go R-C R-C 12k, with 0.2uF to ground feeding 210k with 0.1uF to ground, then your follower.
Hello According to the Barkhausen's criteria, when the gain=1 and the phase shift=180 degree, the system starts oscillating. Therefore for any system to be stable, gain= 0dB and the phase shift = -180degree should not occur at the same time. Now can anyone explain me practically when gain is 0dB why does phase shift shou
The first circuit is a RF amplifier, its output is tuned to a frequency set by C' and L. The second circuit is a self oscillating mixer as found in the front end of a AM radio. L' and C4,C5,C6 tune the oscillator. C and L tune the IF transformer. Third circuit, T2 seems to be an oscillator and T1 an amplifier, beats me whats its all ab
"Costly" ICs or not, they at least need to implement a boost converter, using an inductor/transformer and an oscillator, possibly a self-oscillating switching stage. Achieving low quiescent current and high efficiency is kind of a challenge for a simple low part count boost converter.
It looks like the amplifier(s) are oscillating. It could be at a very high frequency. Have you kept the wire running to the input pin well away from the output pin?, Running the wire to the volume control in screened wire might help. You could try to reduce the high frequency gain by putting a capacitor of 470pF across R4. Frank
The inductor parallel to the crystal is the reason not oscillating at higher frequency. The posted schematic is an working 175MHz overtone oscillator. May need some tuning to get 216MHz, but may not. The choke DR1 makes less RF voltage drop at the source point.
If the resistor is 1 pico-ohm then that's very low. The oscillating loop is getting swamped by the op amp output. The oscillating loop benefits from having a certain amount of isolation. Setting a resistor value to picoohm (microohm would be effectively the same in this case) is a common method to remove it temporarily from a simul
the noise from the bias devices can be mirrored to the main oscillating circuit causing poor phase noise. add capacitor to ground/vdd on your bias nodes to act as a filter (you can implement gm-C filters also) this will help you reduce your flicker noise from the bias device by filtering. increase your device sizes to decrease your noise, and in
typically a number of ring oscillator (RO) types are implemented in test chip: ROs with inverters, buffers, gates (nand, nor,...); RO with different fanouts (FO=1, FO=4,...). RO self oscillating frequency at different conditions (i.e. PVT) give a most timing information dealing with library characterization/verification.
All feedback systems have the potential for oscillating. The trick is to reduce the amount of feedback before the total phase shift goes 180 degrees. This transformer feedback method was invented many decades ago by a US company that made amplifier modules. It was patented. They called it lossless. Prior to that the usual method was a series resist
Hi, this is a SMPS charger based on uc3842 chip and deliver 12V 8A output. the problem is that the supply voltage of 3842 VCC are oscillating and i couldn't fix it at 16V and supply cannot start because 3842 ON volt are 18V. when I remove the chip from circuit it goes to 18V accurately. I tried without transformer but Vcc are not ok. Do it work
There are LO amplifiers in that chip, they may be oscillating. Check to see if you have enough power supply bypass caps, and that the source impedance is not too bad (note that data sheet specifies a 50 ohm source). Maybe put two 3 dB attenuators at the LO in to see if it goes away. Also make sure it is not a ripple on your power supply. If t
There is heavy reason why it is inverted If the gate is non inverting it's easier to fall in self oscillating mode - during some tranition stages the input - output characteristic becomes as OpAmp with big amplification. Like result you can get much easier positive feedback and oscillations if the gate is non inverting. Non inverting gates suffer
Hello! I have a LCD Samsung LE37M87BDX where the picture is black and white! I have measured, in the main board, all of the crystals oscillators and one has 1Vdc in one pin and in the other 3,2Vdc and it is not oscillating. Do you agree that this component is defective? Normally when I turn on the TV all the crystals will oscillate? Even i
You have two different concepts both modelled as "X". There's the X meaning "it could be zero or one, and I can't determine mathematically that it is one or the other". For example when using uninitialized memory, ... There's also a timing violation that may cause metastability. This metastable state is oscillating somewhere inbetween clear zero
Usually simulators don't work very well with oscillators because of the initial conditions of the circuit in spice, I'm not sure that the circuit will start oscillating Alex
I think ωd is a frequency that the loop can sustain oscillating. At the freq, the positive-feedback gain should be bigger than 1. However the accurate theory is unclear. The guess between ω@unity gain and ω@-180° seems reasonable. However the actual oscillating freq depends large-signal characteristic.
I'm trying to simulate a Class D amplifier with hysteretic self-oscillating modulator but the PSS simulation is not acepting the configuration. Basically the self-oscillating system frequency (fs around 500 KHz) will be modulated by an audio signal (fin around 1 KHz) and fs will be varying from 450KHz to 550KHz but in a non-linear fashion since
Since you arent interested in transmitting any real information, I think John's idea of 2 555s (or a 556) is an excellent one; Wire up one 555 to oscillate at around 100hz, and use the output to control the 2nd 555 oscillating at 38khz. At the output of your TSOP, you should get your original 100hz signal; use this to drive a 555 monoshot to get a
Hi, You need to set your oscillator to make sure it is oscillating at 8 MHz. It might be too low for a particular baud rate.
I built a 13.56MHZ RF power amp (4W) however the PA was oscillating and noticed that the AC signal was shorting to ground. However my prof told me to took off the 0.1uF capacitor (C55, grid C3) and and put 1 600pF capacitor(in parallel, to GND) just outside the gate. Note that R58 was not placed in the PA. What is the rational behind it? (referr
Hello, We are driving LEDs for TV backlights. We are doing Analog Dimming, and the LED current maximum is 500mA. We can change the LED current at a speed of 25mA per millisecond. Do you think this will be quick enough? We cannot change the current any faster, as the offline LED driver starts oscillating and switching noisily. (
Regarding your question about simulation, I'll try to answer some of them. 1 - If you are using your crystal at its nominal frequency, then set the beat frequency of the PSS to 80MHz. If you are having your crystal oscillating at another frequency please set that one. 2 - Set the upper limit to half the oscillation frequency. The upper frequency
Hi all, I found when simulating with ADS, the oscillating freq changes when impedance-matching circuits change without chaning DR setting ?Can anybody tell me the reason?Thanks. Yun
The circuit will oscillate with the voltage on C2 oscillating between (V1+Vdd)/3 and V1/3 assuming the opamp has a rail to rail output. To calculate the time period you need to calculate the C2 capacitor charging time from V1/3 to (V1+Vdd)/3 through the RC network supplied by Vdd and the C2 discharge time from (V1+Vdd)/3 to V1/3 through the RC netw
I would highly recommend that you NOT use that circuit. As far as I can tell, it is a injection-locked self oscillating system. Frequency locked systems are NOT phase locked, and you will have a big input to output phase error, and it will be temperature and power supply dependent! Since you are at 60 Hz, I would just use two DC crossing detec
can someone help me with a 12v dc to 220v ac full bridge inverter circuit diagram. the first full wave rectifier(self oscillating eg irs2453d) is connected to the 12v supply, then a transformer, followed by a rectifier, then the other full bridge rectifier.
Hi I have designed lpc 1768 board , all the devices connected to it is working well except RTC,,, i think oscillator is not working,,, things is cross checked and replaced is capacitor from 10pf to 39 pf oscillator and connected 1 megh ohm resistor across the oscillator all these things have performed even though oscillator is