TOTeM frequency change question

[Mike(Mont)]

I got the urge to modify the TOTeM receiver to a lower frequency. Any suggestions on how to do this? I think just change the ferrite windings and C1 and C2. Thanks for your help.

[havoc88]

Hello Mont.

That's correct. By changing the induction of the ferrite rod (more windings to get lower frequency) AND-OR the total capacitance of C1 and C2.
If you have already the coil on ferrite I think that it's more wise to get higher values of C1 and C2 (more than the original total of6.9nF) to lower the frequency of the receiver.

[Mike(Mont)]

Thanks Havoc88. I haven't started the build yet. My Contraption works as is, just seeing what the different receiver can do, or if it will work. Probably make some other mods along the way.

[abdou2014]

I had some problem in the display, during the detection the LED does not turn off when I move away from a ionic source , i think we must modify the threshold with comparator circuit

[Mike(Mont)]

I had some problem in the display, during the detection the LED does not turn off when I move away from a ionic source , i think we must modify the threshold with comparator circuit

Maybe the ferrite rod moved out of place?

[abdou2014]

in passive mode there is this probl?me

[Mike(Mont)]

in passive mode there is this probl?me

No, I am referring to active mode. Sounds like some kind of self-oscillation?

[Mike(Mont)]

Another day, and my mind has changed like the wind. I did some reading and right or wrong I have now decided to hold off on the TOTeM receiver. But maybe another day i will change my mind again and go for it. I am curious to see how it performs, but limited funds right now and I consider it a gamble whether it will work at all for my application. I'm probably better off to modify my existing receiver. Thanks for the help.

[abdou2014]

The problem of the display is also in the passive mode, when you approach to electric source and you go away the led does not turn off ??????????

[Qiaozhi]

If you want to improve the stabilty of TOTeM, then replace the existing 9V battery with a 12V battery, and a 9V linear regulator (79L09).
There is a known issue with the current design that causes the threshold to drift over time, which is caused by a drop in the supply voltage.

[Mike(Mont)]

Thanks, Q. Not a big fan of the 9 volt transistor battery. I prefer to use a 9.6v NiMH like they use for the AirSoft guns or R/C toys.

[Pahom]

Thanks, Q. Not a big fan of the 9 volt transistor battery. I prefer to use a 9.6v NiMH like they use for the AirSoft guns or R/C toys.

A fan for cooling the stabilizer is 9 volts, this is superfluous. Just create fan noise problems. Yes, and if your stabilizer is warming, then somewhere you have problems with either installation or parts.

[abdou2014]

If you want to improve the stabilty of TOTeM, then replace the existing 9V battery with a 12V battery, and a 9V linear regulator (79L09).
There is a known issue with the current design that causes the threshold to drift over time, which is caused by a drop in the supply voltage.

Thank you Mr Qiaozhi , you mean to supply the totem with 12V ?
because I use 4 x 3.7V and a 7809 regulator !

[abdou2014]

[Qiaozhi]

Thank you Mr Qiaozhi , you mean to supply the totem with 12V ?
because I use 4 x 3.7V and a 7809 regulator !

Yes, that's what I'm suggesting, as you have it.
TOTeM does not react in the way you said. i.e. the LED staying on in passive mode after moving away. You must having something wrong somewhere, or you need to calibrate the unit more carefully.