# Search results

1. ### Unclear Transformer Specifications

Thank you all for the information. I should have noticed off the bat that it's output was DC. After finding it, my original idea was to build a Jacob's ladder, but <2mA of output current seems too low.
2. ### Unclear Transformer Specifications

Can someone help me better understand the specs for this old transformer I found? I'm confused why the input and output power see to differ greatly (115V*1.2A ~140W while 40,000V*2mA~ 80W). Also, the fuse rating is unclear to me. Does that mean 1 and 2/10 amp?
3. ### Virtual Ground Voltage Reference

Thanks. If temperatures exceed the commercial range for me, I'll have bigger problems than the amp :-)
4. ### Virtual Ground Voltage Reference

Thanks. The virtual ground circuit is a neat idea, but I'd like to avoid the complexity if possible.
5. ### Virtual Ground Voltage Reference

I'm building an Arduino voltage logger that includes an op-amp (OP27G) as a buffer on the input. Since I'd like to be able to measure voltages all the way down to zero, I want to power the amp with a bipolar supply. My initial thought was to build the rail-splitter below so I wouldn't have to...
6. ### MATLAB User Specifying a Fit Function in a Separate File

I have tried, for example: x = [11/2 11/2 11/2 13/2 13/2]'; % F y = [9/2 11/2 13/2 11/2 13/2]'; % Fprime z = [0.117 0.114 0.110 0.156 0.151]'; ft = fittype('HyperfineShiftFunction( [x, y], Aprime, Bprime, offset )'); f = fit( [x, y], z, ft ) Where...
7. ### MATLAB User Specifying a Fit Function in a Separate File

I have five data points (x,y,z), with two independent variables (x,y), and have written a function in a separate file z = f(x,y,A,B,C), with three undetermined constants (A,B,C). How can I use a Matlab fitting program to try and determine the constants? I've written a fit function before where...
8. ### I Nuclear g-factor

You're right. I was confusing the nuclear g-factor of a proton with the nuclear g-factor of an atom.
9. ### I Nuclear g-factor

Looking at the Wikipedia page for the Lande g-factor, I'm a bit confused. I thought that g_I\approx5.585, that of the proton, but then there is the line saying that https://en.wikipedia.org/wiki/Land%C3%A9_g-factor It makes sense that the nuclear and Bohr magnetons would differ by the mass...
10. ### LaTeX Prevent Latex from Including the Location of Every Citation

Thanks so much. I was wanting to remove them because they seemed to be cluttering the references page. I might just add a note about them, and keep them in place since you're right, they could be useful.
11. ### LaTeX Prevent Latex from Including the Location of Every Citation

Thanks. I think it's in the package files too. I'm going to dig through the assorted files in the folder while I wait to see if the author responds.
12. ### LaTeX Prevent Latex from Including the Location of Every Citation

I think it is defined by the thesis template that I'm using, not Zotero. I've tried changing bibliography styles within the same template, and the problem remains. Using Zotero and bibtex with other templates dies not display the issue. Tried looking at the thesis style in a text editor, but...
13. ### LaTeX Prevent Latex from Including the Location of Every Citation

I'm using Zotero to export my Bibtex file (references.bib), and including it with: \addcontentsline{toc}{chapter}{\bibsecname} \renewcommand{\bibname}{\bibsecname} \bibliographystyle{plain} \bibliography{references} For some reason, in the final References section, it is including a chapter...
14. ### Concerting 0.1" pitch header pins to 0.150"

Thanks for the sugestions. It is two rows of 8 pins. I like your veroboard trick.
15. ### Concerting 0.1" pitch header pins to 0.150"

I made a mistake on a PCB I designed, and have a set of through holes that are spaced 0.150" apart, when the component I want to put into it has a pin-pin spacing of 0.1". Does anyone know of a simple adapter that could go between these two sizes? I'm looking to avoid the time consuming task of...
16. ### Reference Pin on Differential Amplifier

Thank you. Specifically for my circuit I would like: signal in wrt analog ground --> [amp03] --> Arduino+A-D (ref. to Ardunio ground) --> [amp03] --> signal wrt analog ground
17. ### Reference Pin on Differential Amplifier

I want to use a differential amplifier to separate the digital and analog ground portions of a circuit, but am not confident in my understanding of the datasheet of the amps I have on hand (amp03). http://www.analog.com/media/en/technical-documentation/data-sheets/AMP03.pdf I think that...
18. ### HeNe Laser Power Supply Components

I'm a physics graduate student in a lab that routinely uses 18W IR lasers, and I bought some cheap ~633nm laser goggles. I know of no regulations prohibiting such a low power laser in my area. I am more unfamiliar with the HV part of the supply, but with the leads going right into the tube, I...
19. ### HeNe Laser Power Supply Components

Sorry, should have mentioned that the foil-wrapped brick attache to the tube also has "Input:12VDC WMAX:9 Hz:N/A Output: 1.10-1.50KVDC 4.5mA" written on it, so it likely has the oscillator and rectifier built in. The beefy wires that I assume are the HV leads are affixed already to the...
20. ### HeNe Laser Power Supply Components

I recently salvaged a Melles-Griot HeNe laser from an FTIR system. I neglected to save any of the electronics except for what I think is the step-up transformer attached to the laser tube. The laser is "05-LSC-708-540" and the transformer is "05-LPM-850-045". I have a 12V power supply, but was...
21. ### Breit-Rabi Formula Derivation for j=1/2

1. Homework Statement Derive the Breit-Rabi equation in the case that the quantum number j is equal to 1/2, specifically the 1S_1/2 state of Hydrogen. This is the equation describing hyper-fine and Zeeman splitting of the energy levels in an applied magnetic field. 2. Homework Equations We...
22. ### Approximating H Wavefunction Circular State for Large n

I see. In this case I can just use the orthonormality of the spherical harmonics to integrate away the angular dependence.
23. ### Approximating H Wavefunction Circular State for Large n

1. Homework Statement We are studying circular states of the hydrogen atom (states where the l quantum number is = n-1). We are asked to evaluate \langle \Psi_{n,n-1,n-1}| r_{n,l=n-1}|\Psi_{n,n-1,n-1}\rangle . The wave function is that of the hydrogen atom, and the thing we are taking the...
24. ### Starting Motor Without it's Starter Capacitor

I found a motor I think is from an old AC unit in the recycle. It is a 1/4 HP, 265V, 1.20A AC motor. I've been looking to make a low-torque sander and was thinking about using this as a a drive motor. I know the starter capacitor is there to provide an initial burst of current to get it up to...
25. ### Force Computer ATX Power Supply to turn on Without Motherboard

I had tried the 100k because I had a pot on hand and didn't care if it burned out. I'll try to get some power resistors and load both the 5V and 3.3 rails.
26. ### Force Computer ATX Power Supply to turn on Without Motherboard

I've tried resistors up to 100k. I might try loading the ATX motherboard pins themselves instead of the SATA/ATA ones to see if it looks for a motherboard too.
27. ### Force Computer ATX Power Supply to turn on Without Motherboard

One of them has a voltage spike, and the fan does a 1/4th turn before stopping every time I switch it on. I am getting the +5V to the motherboard from both of them. It must be the load. Apparently a DVD drive is not enough of one. I've tried various loads across one of the SATA power outputs...
28. ### Force Computer ATX Power Supply to turn on Without Motherboard

I have that one shorted to common already. Are you talking about the PS_OK wire at pin 8? ATX Pinout
29. ### Force Computer ATX Power Supply to turn on Without Motherboard

I'm trying to re-purpose an old Compaq (and another HP) ATX computer power supply to use as a lab PS. I've seen tons of articles on line about how to do this, for example. I can't get it to even start up though. I have the power-on pin from the ATX connector that goes to the motherboard shorted...
30. ### Four Tensor Derivatives -- EM Field Lagrangian Density

They would then be \partial_kF^{kl} = -\frac{4 \pi}{c}j^l