## Search found 11 matches

Tue Jan 25, 2011 6:55 pm
Forum: Off topic forum
Topic: How to build an electromagnet
Replies: 15
Views: 10340

### Re: How to build an electromagnet

optocoupler (might also be called an optoisolator) is like a relay, but is solid state. Uses a light source on one side to control current flow on the other side. Seem to have lower power requirements than relays /solenoids but I've never had the opportunity to use one.
Tue Jan 25, 2011 12:36 pm
Forum: Off topic forum
Topic: How to build an electromagnet
Replies: 15
Views: 10340

### Re: How to build an electromagnet

You will be severly limited by the voltage / current available. If the max current available is 70mA, and your mac voltage available is 1.75V, you will be limited to 24 ohms resistance in your system. This doesn't give you much to play with when building your circuit. Have you thought about using a ...
Wed Jan 19, 2011 12:39 pm
Forum: Off topic forum
Topic: How to build an electromagnet
Replies: 15
Views: 10340

### Re: How to build an electromagnet

Force = ((N x I)^2 x k x A) / (2 x g^2) N = the number of turns in the solenoid I = the current, in amperes (A), running through the solenoid A = the cross-sectional area, in meters-squared, of the solenoidal magnet g = the distance, in meters, between the magnet and the piece of metal k = 4 x pi x ...
Wed Sep 29, 2010 11:54 am
Forum: Tools and Construction
Topic: 2D PJ Pressure analizer
Replies: 25
Views: 18204

### Re: 2D PJ Pressure analizer

How realistic would it be to use 3 separate images as inputs to set the initial conditions? eg 1 each for initial pressure, temp & velocity. Separate outputs for each of these could be much easier to interpret for analysis. Also, if you are looking at importing in RGB for pressure & temp, would it b...
Mon Aug 16, 2010 12:07 pm
Forum: Jet Vehicles, All Types
Topic: Self launching glider packs a retractable jet engine
Replies: 2
Views: 3844

### Re: Self launching glider packs a retractable jet engine

Being a fairly experienced winch launched gliding instructor, the idea of carying a retractable 'power pod' is always interesting, but I don't see the benefit of jet vs piston power. The speeds & altitudes flown at don't offset the massive difference in fuel consumption. Whilst it will obviously loo...
Wed Apr 08, 2009 11:50 am
Forum: Gas turbine forum
Topic: Parallel Spool engine - Has this been tried?
Replies: 3
Views: 3346

### Parallel Spool engine - Has this been tried?

Most DIY engines are single spool, whether using cetrifugal or axial compressor/turbine. Twin spools are probably out of most 'normal' peoples ability due to the level of complexity involved as they require concentric shafts for the inner & outer stages. Has anyone ever tried using 2 completely sepa...
Wed Sep 17, 2008 6:27 pm
Forum: Off topic forum
Topic: Something I Suspect But Can't Prove
Replies: 7
Views: 3733

### Re: Something I Suspect But Can't Prove

Putting my rusty physics head on again... Question 1, is it a standing wave or a travelling wave? This is a difficult one because of the relationship between the speed of the travelling wave, the desity of air which also defines this and the frequency and wavelength. Change one, and the others tend ...
Wed Sep 26, 2007 1:02 pm
Forum: Off topic forum
Topic: A steam generator with possible over unity
Replies: 32
Views: 21874

### A steam generator with possible over unity

Could this be the effect of releasing energy stored in the water molecule? ie electrons dropping to lower energy levels within the atoms. This could be analogous to the HeNe laser where one atom is excited by RF and then passes the energy by collision to the other which emits at the appropriate freq...
Tue Feb 27, 2007 1:52 pm
Forum: Gas turbine forum
Topic: Johansson´s Pocketbike
Replies: 431
Views: 260231

### Throttle lag - potentially daft idea

Would it be possible to connect a pressure release valve actuated by a solenoid to release excess fuel pressure when closing the throttle? Using a microswitch which is pressed when the throttle linkage is closed, momentarily actuating the solenoid and realeasing some fuel to allow the pressure to dr...
Fri Jan 26, 2007 12:58 am
Forum: Valveless pulsejet forum
Topic: New and Improved Lady Anne
Replies: 179
Views: 78507