Computer Interfacing
Discussions about interfacing and electronics

Reusing the flyback energy

Is it possible to reuse the flyback energy to preserve energy and increase battery lifetime?


       Computer Interfacing Forum Index -> Pulse Induction metal detector
Author Message
New User

Joined: 20 Jan 2009
Posts: 1

Jan 20, 2009 9:16 pm

Hi Lammert, this does look interesting. Being a hobbyist programmer and electronics tinkerer myself I was curious, have you performed any "proof of concept" experiments yet to verify this discrimination is possible?

And IGBT's are becoming more popular. Have you considered these instead of MOSFETs? Google "IGBT" for more info, there is a nice writeup at, and device datasheets can be found at

Alternately, it would be interesting if the reverse spike could somehow be captured (instead of dampened) to recover that lost energy. Just some ideas. You did say the goal was to make the best possible detector. :-)

New User

Joined: 04 Feb 2009
Posts: 2
Location: Switzerland

Feb 04, 2009 7:01 pm

It is possible to recover some of the energy of the Flyback, but at the penalty of loosing several uS of time for the first sample.
In the case of the detector described above, this would mean loose the discriminating.
Site Admin

Joined: 13 Mar 2007
Posts: 145
Location: Netherlands and Kazakhstan

Feb 04, 2009 7:38 pm

Energy consumption is not the main concern in the design. I try to keep the electronics part as simple as possible and adding extra circuitry to store the flyback energy would be against that design principle.

Because the pulse width and frequency is digitally generated it is easy to implement a software controlled energy saving mode where there are less pulses generated per second. Sending less pulses per seconds will decrease the energy consumption proportionally.
New User

Joined: 04 Feb 2009
Posts: 2
Location: Switzerland

Feb 05, 2009 7:14 pm

IGBT's are at 150khz now, but I still prefer the Mosfet.
A high pulse rate allows more integration or averaging of the signal, resulting in a lower lower noise factor.
as you say, it is a trade-off with power consumption.
It might be interesting to calculate the break even point between power consumption and signal resolution.
Is there somebody around who knows how to do that?
New User

Joined: 20 Apr 2009
Posts: 1

Apr 22, 2009 8:51 am

Hi Lammert,

Nice approach to make a better metaldetector with DSP.
Is there any time plan to get the firts proto to work?
I like to build the detector myself because a
PI disc detector is very welcome to me!!
Best regards,


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