Regulator minimum capacitor ESR

Started by Mr.CRC in sci.electronics.design10 years ago 17 replies

Greetings, I'll be using a TI TPS767D301 LDO to power my DSP. I find it easier to deploy ceramic caps rather than Ta, since it's less trouble...

Greetings, I'll be using a TI TPS767D301 LDO to power my DSP. I find it easier to deploy ceramic caps rather than Ta, since it's less trouble fussing with CAD libraries, making sure the parts I can order fit the pads, etc., or rather than building my own Ta cap lib. The point is, the LDO wants a min ESR of about 50 milliohms, but a parallel combo of many ceramic caps is likely to be low...


Solar panel charge controller

Started by Daku in sci.electronics.design10 years ago 27 replies

Could some electronics guru please clarify the following ? Almost all schematics of solar panel power conditioning electronics starts with a...

Could some electronics guru please clarify the following ? Almost all schematics of solar panel power conditioning electronics starts with a charge controller. What is the purpose of this charge controller ? If it is to stabilize the current/voltage from the solar panel, why not use a large capacitor, as the solar panel output is DC. Any hints etc., would be greatly appreciated. Thanks in ...


Can You Top This

Started by brent in sci.electronics.design10 years ago 45 replies

In a game of "can you top this"..... I worked at a small factory where they made condenser capacitors for cars. Worst job of my life. I...

In a game of "can you top this"..... I worked at a small factory where they made condenser capacitors for cars. Worst job of my life. I welded a bracket to the can thousands of times/day. The actual capacitor was like a roll of toilet paper consisting of foil and plastic rolled together...... So I am working at my station near the back of the plant and the whole building kind of sha...


High voltage Capacitor

Started by Jessica Shaw in sci.electronics.design10 years ago 17 replies

Hi, I am using a series resonant LC circuit. The diagram of the circuit is given...

Hi, I am using a series resonant LC circuit. The diagram of the circuit is given below http://img269.imageshack.us/img269/8108/seriesw.jpg I was operating it at 100KHz but now I am operating it at 75KHz inorder to pump more current. Voltage across L1 = 450 V Voltage across L2 = 450 V Frequency = 75KHz Current = 19A peak to peak Capacitor = 45nF I am looking for a capacitor th...


How is this IC powered?

Started by Bob Engelhardt in sci.electronics.design10 years ago 14 replies

I brought home a fence charger from the dump, hoping that it was there due to some simple malfunction that I could fix. On opening it up, I...

I brought home a fence charger from the dump, hoping that it was there due to some simple malfunction that I could fix. On opening it up, I found no blown fuse or other obvious problem. I found the circuitry interesting: it uses a 7-bit ripple counter IC to count 60 Hz pulses, with a 64-count triggering an SCR to dump a capacitor into a high-voltage xformer. I.e., the fence is pulsed ...


Spice Modeling Resistors with Distributed Capacitance

Started by Jim Thompson in sci.electronics.design10 years ago 8 replies

I've encountered a Spice model problem with SilTerra high resistivity poly resistors... They model the distributed capacitance by lumping 1/2...

I've encountered a Spice model problem with SilTerra high resistivity poly resistors... They model the distributed capacitance by lumping 1/2 of it on each END of the total resistance, rather than a multi-lump resistor/capacitor :-( Anyone know of a rule-of-thumb for minimum number of lumps for reasonable accuracy? I'm operating at 100MHz. Thanks! ...


6-layer PCB stack up

Started by Mr.CRC in sci.electronics.design10 years ago 37 replies

Hi: I'm making a 6-layer PCB for a TI DSP, fit onto a 168-pin SDRAM DIMM module form factor. I'm trying to decide if I should stack the...

Hi: I'm making a 6-layer PCB for a TI DSP, fit onto a 168-pin SDRAM DIMM module form factor. I'm trying to decide if I should stack the layers like: 1. Top signal layer 2 signal 3.3V plane GND plane layer 5 signal Bottom signal or 2. Top signal 3.3V plane layer 2 signal layer 5 signal GND plane Bottom signal #1 is preferable for providing a tight coupling capacitor...


PSU capacitor choice

Started by Cursitor Doom in sci.electronics.design2 years ago 15 replies

Greetings, gentlemen, I'm attaching a scan of the rectifier board from an HP8547A network analyser. I'm just wondering how the designer(s)...

Greetings, gentlemen, I'm attaching a scan of the rectifier board from an HP8547A network analyser. I'm just wondering how the designer(s) arrived at the choice of value for the caps across the incoming supply from the mains transformer secondary windings (the caps immediately before the bridge rectifiers)? In case you can't make it out, the values are 0.047uF, 0.22uF, 0.47uF and 0.04...


Favourite parts with off-label uses?

Started by Anonymous in sci.electronics.design2 years ago 142 replies

Following up on blocher's sterling work,(*) Many of us use parts off-label, often very successfully. A few examples: SAV-551+ pHEMTs make...

Following up on blocher's sterling work,(*) Many of us use parts off-label, often very successfully. A few examples: SAV-551+ pHEMTs make very good wideband bootstraps. Their f_max is around 12 GHz, but they're amazingly stable. 74HC4352s make good flying-capacitor diff amp front ends. TMUX1511s make very nice analogue lock-ins--their Coff*Ron FOM is almost in a class with relays, but...


Parallel LC Circuit

Started by Jessica Shaw in sci.electronics.design9 years ago 62 replies

Hi, Link 1 (Helmholtz coil Specifications) : http://img600.imageshack.us/img600/7020/hhcf.jpg Link 2 ( Block System Diagram):...

Hi, Link 1 (Helmholtz coil Specifications) : http://img600.imageshack.us/img600/7020/hhcf.jpg Link 2 ( Block System Diagram): http://img836.imageshack.us/img836/536/systemblockdiagram.jpg I am trying to power up the following 22 uH inductance coil (secondary coil) with 115nF capacitor in parallel at the resonant frequency of 100KHz using Helmholtz coil. The load connected to the sec...


Capacitor codes

Started by Paul Hovnanian P.E. in sci.electronics.design10 years ago 26 replies

I've got an axial lead polarized cap with the following markings: 1K 50V Its about 0.1 in diam x 0.3 in long Now, I've seen 1K as a...

I've got an axial lead polarized cap with the following markings: 1K 50V Its about 0.1 in diam x 0.3 in long Now, I've seen 1K as a picofarad value, which would make this a 1nF cap. But this thing is big compared to other caps of this rating. A .001uF 1KV ceramic is much smaller. And this doesn't make sense in the circuit its in. In other contexts, the K letter code defines the tole...


Switching current limiter for safe charging of large capacitors, and short circuit protection

Started by P E Schoen in sci.electronics.design9 years ago 26 replies

In a previous post about minimizing spikes on a square wave push-pull=20 transformer drive, my simulations discovered a very large and...

In a previous post about minimizing spikes on a square wave push-pull=20 transformer drive, my simulations discovered a very large and probably=20 destructive current surge due to the large capacitor load on the output = of=20 the step-up transformer and FWB. I proposed using a brute force linear=20 current regulator, but the SOA of the transistors would be exceeded. I = need=20 an output o...


simple opamp amplifier circuit

Started by panfilero in sci.electronics.design9 years ago 23 replies

I'm simulating on LTSpice, a simple amplifier circuit with a 2.5V offset, but if I don't include a capacitor on my input my output hits the...

I'm simulating on LTSpice, a simple amplifier circuit with a 2.5V offset, but if I don't include a capacitor on my input my output hits the rails... why is this? The link shows what I'm doing in LTSpice thanks http://i555.photobucket.com/albums/jj477/panfilero/Capture-1.jpg


So, where's the catch?

Started by Tim Wescott in sci.electronics.design9 years ago 32 replies

See the LTSpice circuit. It started out with me asking myself "how can I make an integrator that works fairly well, and uses a honkin' big...

See the LTSpice circuit. It started out with me asking myself "how can I make an integrator that works fairly well, and uses a honkin' big electrolytic capacitor?" And it ended up here. R4/R3 must equal R1/R3 for proper integration action. Output comes off of the op-amp. The integrator gain is (1 + R2/R1)/(R4*C1). The way the circuit works is whacky, and the linear range of input...


Switched Cap ADC Residual Voltage

Started by Tim Wescott in sci.electronics.design9 years ago 9 replies

Any good white papers out there on the residual voltage to expect on a switched capacitor ADC after it reads a channel and goes on to read the...

Any good white papers out there on the residual voltage to expect on a switched capacitor ADC after it reads a channel and goes on to read the next one? Assuming that it's not horrendously design dependent, of course. -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wes...


I think I now know what the SAC722 is and the function of the board.

Started by Jamie in sci.electronics.design9 years ago 1 reply

Earlier I asked if any one had some data on a Motorola part "SAC722" and I have not had any response to it, however, I think I now have it...

Earlier I asked if any one had some data on a Motorola part "SAC722" and I have not had any response to it, however, I think I now have it all under the hood. These units appear to be TRIACs, and there are two of them in series, maybe for redundancy? Any way, there is a REED contact envelope in there with a couple of turns on it that monitors an 1/2 HP AC capacitor start motor. ...


capacitor selection

Started by Jon Elson in sci.electronics.design9 years ago 37 replies

Hello, all, I have been using metallized polyester film capacitors in the output filter of a PWM servo amplifier. I recently discovered that...

Hello, all, I have been using metallized polyester film capacitors in the output filter of a PWM servo amplifier. I recently discovered that when the PWM duty cycle is near 50%, these caps can get quite hot. Perusing the data sheet, it appears that I am running above the manufacturer's current rating in that condition. Can anyone recommend a capacitor around 10 nF and 250 V DC rating t...


butterfly laser

Started by John Larkin in sci.electronics.design9 years ago 2 replies

Got this on ebay, milled the lid off to see what's...

Got this on ebay, milled the lid off to see what's inside. https://dl.dropbox.com/u/53724080/Lasers/Butterfly_ebay_2.JPG https://dl.dropbox.com/u/53724080/Lasers/Butterfly_ebay_Dyno1.jpg I haven't figured out the circuit with the inductor and, possibly, a parallel-plate capacitor. Bias tee? The laser and feedback photodiode are apparently sitting on a TE cooler and maybe a BeO in...


HVAC capacitor questions

Started by mook johnson in sci.electronics.design9 years ago 34 replies

I have a 4 ton Carrier A/C that the original GE cap (Dual 60uF/5uF 440VAC) went out last summer in ~May. It was about 6 years old. The top was...

I have a 4 ton Carrier A/C that the original GE cap (Dual 60uF/5uF 440VAC) went out last summer in ~May. It was about 6 years old. The top was bulged badly so it was pretty clear the capacitor was bad. Went to granger and found a Dayton capacitor that had the same ratings but slightly smaller diameter (2.5 vs 2.75"). http://www.grainger.com/Grainger/DAYTON-Dual-Motor-Run-Capacitor-2M...


Voltage across Run cap in fan motor

Started by mook johnson in sci.electronics.design9 years ago 1 reply

While replacing the run/start capacitor in my AC unit, I wondered how necessary was it to use 440V caps in a circuit being fed by only 240V. ...

While replacing the run/start capacitor in my AC unit, I wondered how necessary was it to use 440V caps in a circuit being fed by only 240V. The cap is a dual 60uf and 5uF in one package. The 5uF feed a 1/4HP fan and the 60of feeds the compressor (herm). I measured the voltage across the input with my meter and it read 230VAC at 60Hz. I measured the voltage on the capacitor from C t...