Replies to Minipulse Plus

[geoscash1]

Thaishine on ebay has free shipping and excellent parts prices.. NE5532's are approx. 23 cents each.. 20 for $4.69
http://www.ebay.com/itm/20-x-NE5532-...item33608b19ab

[Dean Sarelius]

Hi Mick,

Thank you for your advice I will try the LM4562 as you suggested...!

[bernte_one]

hello andy,

when can we order a kit for MP+ ?

[silverdog]

Ok, i have just added 6 kits to the shop

Please order just one each for now so as many people can try and provide feedback

I will be ordering more this week so there will be plenty more in a couple of weeks

[Davor]

I just ordered it

[bernte_one]

me too, thx

regards

[sinclairuser]

bought a kit today, to be honest i expected them to go really quickly, i have been checking andy's site every couple of hours for the last week, but stopped yesterday when i bought the board, then i came here earlier and saw he had added them to the site, so i went for a look, kits were in stock so i grabbed one, at least i will have a spare board now.
thanks andy.

[Dean Sarelius]

Hi Silverdog,
Not sure if you have already shipped my parts if you haven't then I would like to convert to the kit thanks but if you have already then no prob..!
Cheers,
Dean

[sinclairuser]

hi all i have been looking at the original schematic, and the goldscan schematic.
and i think i have worked out what the extra components around and including PL5 were for, if you compare the schematics, it looks to me like a connection for a meter, like the GS had, not all the PL5 connector obviously, but if you were adding one its in the right place, check it out.

[Davor]

A few thoughts...
I think I know exactly how to add ground balance to minipulse. Surprisingly it should be fairly simple. I thought of avoiding GB with minipulse, but then again - I'd be using it on some difficult terra rossa terrains, so why not?!
I'm also considering a sort of spectrum spreading add-on for 555 time base that should improve its performance near powerlines. Or not. It may be worth a try.
The EF timeslot effectively turns the integrator into a chopper that partially takes care of 1/f wandering offset effects. TL062 is not particularly bad in 1/f region, but perhaps some quieter op amp could do better in its place.
I'm also considering current limitation at Tx and dual coil configuration with possible balanced Rx input to avoid shielding.

[6666]

possible balanced Rx input to avoid shielding.

Please tell us more , thanks.

[Davor]

There is not much to tell right now. First I'll have to adapt some balanced front end that is referenced to a positive rail to enable using it with classic shielded monos. I'm quite happy with my shieldless VLF coil that has Rx in balanced configuration with centre tap. It requires a differential front end, and there is no "wet grass" or any other effect related to poor shielding to behold, yet it has no shield at all, and I can use a classic single ended shielded coil with the very same front end as well. The only downside is the noise performance as the single ended front end has half the noise power than balanced one made with the same components. It is not much of a drawback considering the benefits.
I like to call shieldless coils FKK (Freikörperkultur) a German term for the nudist movement.

[6666]

Thanks Davor, looking forward to see your ideas.

[sinclairuser]

has anyone started yet?, i have 5v-, 5v+ and half the components for the next stage, but i'm finding it small and fiddly, its ok i will manage but newbies may struggle, you may want to increase the board size a little to increase trace gaps, just an observation.
i will plug away with this as i intend to fit this board into a 1266x case and handle, its the perfect size for that.

[johnandles]

has anyone started yet?,

Just received PCB today here in Southern OZ...must have been a good South Easterly blowing! very quick.
Collecting parts,then get stuffing....
Cheers
John