large & efficient electro magnet

[Melanie]

All you ever wanted to know...

http://info.ee.surrey.ac.uk/Workshop...ils/force.html

Wiki I would not trust.

[therian]

Thank you that was very useful information

just one more question, can I have an advice how to safety connect digital scope to read the coil, I have 100x probes but they home made and really noisy so I want to use 10x one and voltage might exceed them and I don't know what will happen to scope then.

[Melanie]

and I don't know what will happen to scope then

You will destroy it. A coil with the kind of inductance you are winding will probably have an emf of a few kV... most modern scopes only have a 50v tollerance.

Use your probe set to 10:1 and use a Resistor divider chain of another 10:1. If the Bottom Resistor is 1M it won't load the circuit. That should give you a 5kV operational tollerance.

[Luciano]

Hi,

Pulse motor evolution. (Moto-perpetuos made in Seattle USA).


(Make sure your PC speakers are on).

Best regards,

Luciano

[Melanie]

Yeah, right... more like moto-preposterous...

Would be more meaningful if he showed CURRENT-IN versus CURRENT-OUT as well as the voltage which on it's own is irrelevant.

What he's trying to make you believe is that his Power-Input, less frictional losses, less conversion losses, less electrical losses, is still a NET GAIN?

[therian]

will this wok as 100:1 probes ?



------/\/\/\99K\/\/\--------------------> to scope
******************|
******************/
******************\
******************/
*****************1K (1.001К)
******************\
******************/
****************** \
******************|
----------------------------------------> to scope
all resistors 1W

what about AC is it safe for AC


I already build this probes but they so noisy, pick up all wiring

------/\/\/\25M\/\/\-------------------->to scope
******************|*****|******************
******************/*****| ******************
******************\*****|******************
******************/*****\/******************
*****************1M****--******************
******************\*****| just in case 2 zener diodes( which will newer switch because of low current)
******************/*****--******************
****************** \****/\******************
******************|*****|******************
-------/\/\/\25M\/\/\------------------> to scope

[Melanie]

Looks good if in your opinion 100k isn't going to adversely load your circuit.

Safety.

If you are connecting a scope to an AC supply (eg Supply Mains out of the wall), then the 0v on your scope (unless it's a Battery scope) will almost certainly be Ground/Earth. If you live in a country like the USA which controls population growth by allowing it's citizens to plug their Power Cords into the wall either way round, then you can have a situation where the scopes 0v (Earth) is being connected to the Live in your device under test.

Either...

(a) For Test purposes feed your device through a 1:1 ISOLATING Transformer (this is the preferred method as your device will no longer be LIVE - it'll still be dangerous but not LIVE relative to EARTH), or...

(b) Isolate your scope through a 1:1 Isolating Transformer (not the brightest option as your scope can then become LIVE and rubber-soled shoes and Latex gloves are then recommended).

Why then even suggest option (b)? Well your project/device just might suck 20kW and you only happen to have a 200VA Isolating Transformer!