Replies to Minipulse Plus

[Qiaozhi]

Did I miss power consumption info? Thanks for check Qiaozhi.

This will depend on the TX pulse rate and the pulse width, but with the current settings (1000pps and 57us) the current consumption is 87mA.

[WM6]

Did I miss power consumption info? Thanks for check Qiaozhi.

[Qiaozhi]

Hi
opened your gerba files ok and found very interesting, well done
If there is going to be along delay in getting lay files for your rev b may deside to use rev a and just change relevent mistake 4"x3.5" is a ok size for me, top layer copper print is easy bottom I need to spend more time on getting it black and white.
How is your test Jig fairing? because im eager to start experiments, dont care if its got teething problems , got all the bits although my MC14538BCP has a G on the end , but should be ok, what do you think?
Regards

The test unit is working fine, but Silverdog is currently very busy and having difficulty finding time to replicate the design.
There are a few errors that need to be corrected in the wiring, plus some component changes. That's why REV-A boards will not be made available.
Please be patient and wait for REV-B.

[satdaveuk]

Just received 3 PCBs today from Siverdog. Once I've got the components together I'll build one unit to check everything is OK, and then write a "build document" to try and prevent the same failures that Surf-PI builders are experiencing.
Be patient though, as this is very much a background task.

Hi
opened your gerba files ok and found very interesting, well done
If there is going to be along delay in getting lay files for your rev b may deside to use rev a and just change relevent mistake 4"x3.5" is a ok size for me, top layer copper print is easy bottom I need to spend more time on getting it black and white.
How is your test Jig fairing? because im eager to start experiments, dont care if its got teething problems , got all the bits although my MC14538BCP has a G on the end , but should be ok, what do you think?
Regards

[greylourie]

Thanks Davor.

[Davor]

Basically it is only size, and perhaps cost. Otherwise they are quite nice.
They have quirks of their own, but you'll hardly notice any at metal detecting frequencies.

[greylourie]

This is a very interesting topic that has been puzzling me a bit. I have seen a P.I circuit which makes use of 2.2uF poly with 22.5 mm (or similar) spacing, for the SAT. But when I look at other circuits for a point of reference, I cannot find an example using such a similarly substantial cap. So what I was wondering, is there anything wrong with using larger value poly caps other than the physically large size and subsequent constraint it might pose on circuit layout and pcb real estate ?

And I faltered when trying to modify and place a 2 pole filter in another (Goldscan) circuit, when I ended up with a large cap value for the first stage - whilst trying to maintain close to original R / impedance values. KingJL seemed happy with using 1uF in part of his 2 pole filter for his modded Hammerhead.

Is there a rule of thumb, or guide to the min/max values of poly caps for use in LP/HP filters for P.I receive chains ?

[eogeo]

Thanks for the feedback Davor. I will put ceramic caps further down the list.

[Davor]

Depends.
Ceramic caps pose very little inductivity, and hence they are good for RF filtering jobs, but they suffer from non-linearity, and piezo-like effects. I still have a few that I keep for educational purposes that buzz quite audibly when audio is applied to them. They have abysmal distortion, and yet, they are not too bad for RF. The only place for those in metal detectors is decoupling.
Polys are OK for audio, but at large capacitances they grow too big.

[eogeo]

Are there any guidelines or rule of thumb for selecting the types of non-electrolytic capacitors in detector circuits and are some types more suited to some parts of the circuit than others? The parts list suggests poly. capacitors and I was looking at purchasing the poly caps in the attached images but noticed that different looking caps had been used in the image in post #27 which seems to suggest that more than one type of capacitor would be suitable. In searching for caps I have also come across ceramic NPO/COG types that look like they could be suitable for some areas, are they worth considering? Thanks.

[Qiaozhi]

I been trying to look at the gerba files In the sticky, tryed eagle sprint designspark easeypcb etc, Do I need something different?
Just wish they would use a common format between themselfs it would save so much hassel.
Maybe here in Geotech we should show a example and all use same format.
I dont care which one it is what ever you all deside I will go along with.
I jumped the gun you say easy pc top of this page so will download the demo and see what happens
Regards

The Gerber files contain G-codes that the PCB manufacturer uses to make the boards. These are not layout files.
You can view the Gerber files using the open source "Gerbv" Gerber File Viewer. This is a native Linux application.
For Windoze, there is apparently an experimental beta version.

Failing that, you could try GerberLogix for Windoze, which is also free.

[satdaveuk]

I been trying to look at the gerba files In the sticky, tryed eagle sprint designspark easeypcb etc, Do I need something different?
Just wish they would use a common format between themselfs it would save so much hassel.
Maybe here in Geotech we should show a example and all use same format.
I dont care which one it is what ever you all deside I will go along with.
I jumped the gun you say easy pc top of this page so will download the demo and see what happens
Regards

[satdaveuk]

I'm currently waiting for Silverdog to replicate the final design before updating the files.

Your a Star, Thank You

[Qiaozhi]

Is there any chance of putting the latest silverdog lay files on here for those who want to make there own circuit boards?
Thanks in advance
Regards

I'm currently waiting for Silverdog to replicate the final design before updating the files.

[satdaveuk]

no need for gold detector.
minipulse will do for me ,i only want to build that as its one of eric's designs, and has the edge on the barracuda.

Haha we dont know yet till we built it
But like you Sinclair will be building it with positive thoughts and baited breath

Is there any chance of putting the latest silverdog lay files on here for those who want to make there own circuit boards?
Thanks in advance
Regards