Romero's experiments and OU principles

[duff]

I have email the wire mfg and requested the specs on the wire Romero used.

Will post their response.

[neptune]

From my notes at the time , Romero quoted the resistance of each coil as 1.7 to 2 ohms . Some one suggested on one of the threads to cause the coil to "ring" and use a scope to find its resonant frequency . We do not all have scopes . If someone with a scope can do this ,and tell us what the ideal resonant frequency is , there are easier cheaper ways to measure it . One way would be to connect the coil , with its added cap if any , into a one transistor radio frequency oscillator , and listen for it on a receiver . Or for those with radio tech experience , use a grid dip oscillator .
       If we work on one coil , or one coil pair at a time ,on the bench , with a means of measuring the frequency , we can tune it simply by winding it with too many turns , and remove turns until the frequency rises to the desired result .I favour the one-transistor-oscillator circuit method , and a receiver or frequency counter to measure the result .
EDIT . Maybe it will suffice to just adjust all coils to have the same frequency , as the ideal figure will be RPM dependent.

[maw2432]

From my notes at the time , Romero quoted the resistance of each coil as 1.7 to 2 ohms . Some one suggested on one of the threads to cause the coil to "ring" and use a scope to find its resonant frequency . We do not all have scopes . If someone with a scope can do this ,and tell us what the ideal resonant frequency is , there are easier cheaper ways to measure it . One way would be to connect the coil , with its added cap if any , into a one transistor radio frequency oscillator , and listen for it on a receiver . Or for those with radio tech experience , use a grid dip oscillator .
       If we work on one coil , or one coil pair at a time ,on the bench , with a means of measuring the frequency , we can tune it simply by winding it with too many turns , and remove turns until the frequency rises to the desired result .I favour the one-transistor-oscillator circuit method , and a receiver or frequency counter to measure the result .
EDIT . Maybe it will suffice to just adjust all coils to have the same frequency , as the ideal figure will be RPM dependent.

Neptune,  not sure if this would help but I have seen some multimeters with Frequency measuring capabilities.
For example this on sale for 19.99

http://www.kitsusa.net/phpstore/html/M-118-12-Digit-DMM-With-Capacitance-and-HFE-and-Frequency-822.html

Bill

[neptune]

@maw2432. Yes , such a multimeter would help . But we still need to wire the coil temporarily into an oscillator circuit to get it to oscillate . The choice of oscillator circuit is important . We cannot use a Hartley circuit because it needs a coil tap . A Colpitts circuit needs 2 external caps . There is a circuit I used about 40 years ago . It used a NPN transistor with the tuned circuit as collector load . A potential divider set the base bias , with 2 small caps in parallel with these bias resistors . At the expected frequency , a small cap , say 10pf needs to be connected between collector and emitter to provide feed back . That is all there is to it .
         An altogether simpler approach is to just use a suitable meter to measure the inductance of each coil . This is not so accurate as 2 coils may have the same inductance , but different self-capacitance , and thus a different resonant frequency . So I think the above oscillator will be the answer . Perhaps someone could draw a diagram with suitable component values , as I am not able to do this , and have only used this circuit at Very High Frequencies .

[teslaalset]

FYI, I posted an update of my previous reply with some interesting links.