555 timer/inductor in ltspice problem

[large_ghostman]

View attachment 63952


hi ive been trying to sim this circuit in LTSpice but i am unable to do it what i am trying to do is alter the inductor by doing a sweep so i can see the change in the output frequency the isea is to try and simulate metal coming into contact with the inductor coil as i am trying to design a metal detector for the robot
thank you very much lg

 

[ericgibbs]

View attachment 63952


hi ive been trying to sim this circuit in LTSpice but i am unable to do it what i am trying to do is alter the inductor by doing a sweep so i can see the change in the output frequency the isea is to try and simulate metal coming into contact with the inductor coil as i am trying to design a metal detector for the robot
thank you very much lg

Hi Logan,
This is how you STEP the inductor..

E

 

[large_ghostman]

could i have the file please mr gibss so i can see the way its done
thank you

 

[ericgibbs]

could i have the file please mr gibss so i can see the way its done
thank you

hi,
Here it is, not much change in frequency for a change in inductance, do you know why.??

 

[large_ghostman]

hi,
Here it is, not much change in frequency for a change in inductance, do you know why.??

is it because the inductance change chanegs current and the frequency of the circuit is altered by voltage (the voltage devider)??
thank you for the file now i can see if placeing the inductor in diff parts of circuit has any effect

 

[large_ghostman]

when i try and open the file all i get in ltspice is a page of numbers ?? no symbols

 

[large_ghostman]

ok i sorted that it kept saving as a text file!!! now i have the drawing but dont have the 555 timer you used lol i will try and find it and add it

 

[ericgibbs]

is it because the inductance change chanegs current and the frequency of the circuit is altered by voltage (the voltage devider)??
thank you for the file now i can see if placeing the inductor in diff parts of circuit has any effect

hi,
Your 555 runs at ~1KHz.

You have a 330uH inductor, the impedance of the inductor at 1KHz is = 2*∏ * 1000 * 330*10-6 = 2 Ohms

Consider when near a ferrous object it goes to 1000uh , thats only 6 Ohms................ a 4 Ohm change has a very small change in frequency

These are rough values,using a sine wave calculation for a square wave signal, but they will give you a clue.

 

[large_ghostman]

could you explain the calculation please i can understand 2*pi(i think its pi symbol)*1000(the frequency?)*330(the inductor)but i dont know where the 10-6 comes from?? by the way i am using 5v input not 12
thank you for your time mr gibbs

 

[large_ghostman]

after thinking about it maybe i am looking at it wrong would it be better if i just used the inductor to produce a magnetic field via a pulsed vo9ltage and used a hall sensor to measure this with the assumption it would be accurate enough to pick up the difference in the field when the field came accross metal?

 

[ericgibbs]

could you explain the calculation please i can understand 2*pi(i think its pi symbol)*1000(the frequency?)*330(the inductor)but i dont know where the 10-6 comes from?? by the way i am using 5v input not 12
thank you for your time mr gibbs

hi L,
Your original 555 drawing shows a 12V supply.

Your 330uH coil is a 330 micro Henry, a micro is 10-^6 ie; 0.000001 so the coil is 0.000330Henry

The ∏ symbol is 'pi'

Ref post #10. I do not know the full specification of your inductor.???

 

[large_ghostman]

thank you for that explanation i am not sure all the specs i will ask dad later if he has a sheet for it (probaly will somewhere)