Voodoo Main Discussion

[6666]

Hello Don, would you know approx how many micro seconds after the TX pulse that your 4066 operates to take your Disc sample ?. thanks

[SilverSurfer17]

Im just excited i thought id have to drive hours for good places to detect then did some research of my town and found out it was built in 1835 and the stagecoach trail runs right through my town so i know now there are old coins around ill start at the river where i know people would bath and where the old hotel built in 1842 used to be

[SilverSurfer17]

Yeah i watch the news and knew it would take longer most of the time anything from the UK takes 10 days its going on 17 now never thought id see anything take longer then china lmfao but i hope those vaccines start flippin the script

[MartinB]

Man the UK must of got over run by Rona i ordered a speaker from China 4 days after i ordered my board and just got the speaker and still no board

It is pretty rough over here. We are in lockdown which causes all sorts of delays. Not many planes flying to the US either

[SilverSurfer17]

Man the UK must of got over run by Rona i ordered a speaker from China 4 days after i ordered my board and just got the speaker and still no board

[Altair]

Many thanks Ivconic!

[dfbowers]

Gerbers:

Thx!!

[waltr]

Hi Ivconic , good work, I have had a look at the diode I requested but it appears to be drawn in parallel which requires a fuse to be placed in power lead which is ok it will work, but people seem to get it wrong and dont add the fuse

but what I was asking for was a series diode something like a 1N5822 40v 3A Schottky, if people dont want it they can short it out, what are your thoughts ?

That is a good solution for preventing letting out the magic smoke.
Many say this drops the Voltage as heat in the diode. Here is why this is actually a good thing.

The Battery Voltage is 12V (12.5 to 14.4 for Pb acid or 11.1 to 12.4 for 3S LiPo). The Regulator is 5V out and if not an LDO needs a minimum of 3-4V above output, around 8-9V. Therefore the diode drops 0.4V (Schottky) so still plenty of input Voltage overhead.
Also, the Voltage the regulator drops is turned to heat. So say 250mA Draw on the 5V regulator produces (12-5) * 0.25 = 1.75 Watts of heat. The diode drops 0.4 so with a diode the regulate produces (12-0.4 -5) *.25 = 1.65Watt, and the diode produces 0.1 Watt. Same total amount of heat but spread over two parts.

[ivconic]

Gerbers:

[ivconic]

No sweat.

[6666]

This need to be checked by "neutral eyes":

Hi Ivconic , good work, I have had a look at the diode I requested but it appears to be drawn in parallel which requires a fuse to be placed in power lead which is ok it will work, but people seem to get it wrong and dont add the fuse

but what I was asking for was a series diode something like a 1N5822 40v 3A Schottky, if people dont want it they can short it out, what are your thoughts ?

[dfbowers]

Parts, parts, parts.. where does everyone order parts from? I realize we are from all around the world.
Here in the US I use Digikey, Mouser and for older stuff sometimes Jameco.
Reason I ask, for some sources we can share a shopping cart. I have some of the VooDoo components already ordered but I spent a few hours building the shopping cart. I can share what I have if someone would like to check it over.. or if you have an old shopping cart and have a working Voodoo.. let us know.
Don..

[Qiaozhi]

Which capacitor are you referring to? I've been looking at C31 top of schematic. Doesn't look like a differentiator. https://www.geotech1.com/forums/atta...2&d=1609969536

it's not a differentiator, it's a sampling integrator.
The differentiating filters I was referring to are in the Voodoo circuit.

[ivconic]

This need to be checked by "neutral eyes":

[green]

The extra capacitor is not necessary in the Surf-PI derived circuit because the sample gates and the opamp integrator together form a "sampling integrator".

In the Voodoo circuit the filters are differentiators, so there's a capacitor at the output of the sample gates to create a sample-and-hold circuit. Without the SAH capacitor the signal suffers a large drop in amplitude during the TX period.

Which capacitor are you referring to? I've been looking at C31 top of schematic. Doesn't look like a differentiator. https://www.geotech1.com/forums/atta...2&d=1609969536