complete project

[mschmahl]

Updated Schematic in PDF and for Designspark

[Tinkerer]

Hi Tinkerer, thanks for posting the link to Diptrace EDS.

As a matter of interest and sorry to all being off topic, I read a post of your's from early 2011 and i gathered that you may have been using Diptrace and now changed over to Designspark. Correct?? and if so why??

I have downloaded Diptrace and trying to learn it.

Cheers Sid

I downloaded Diptrace, but never got to really use it. When DESIGNSPARK appeared, I looked at it and found that it is the first full size, no restrictions EDS, with 3D, SPICE simulation and a parts inventory of 85,000 parts in 2D and 3D, totally free with no strings attached and no limitations. Regular free updates, tutorials, support and more.
You also get a BOM that is linked to a parts catalog of a worldwide distributor and Datasheets.

It is just too good to be passed by. Now that I am getting used to it I don't think I will ever change.

Tinkerer

[Tinkerer]

Thanks mschmahl for posting the updates.

Some diodes in the RX circuit have a prefix 2Nxxxx. what should they be?

Cheers Sid

Thanks for the feedback. As you see on this schematic, it is a work in progress. The audio with the 4046 worked, but I was trying to improve on it. This is why we have another audio, using a 555 floating on the page. For the 2 diodes in question I used yellow LED's with a forward voltage drop of about 2.4V.

It is extremely expensive for me to buy parts here, so I use what is available in the parts box. Not always the most appropriate.

All the best
Tinkerer

[Tinkerer]

@ tinkerer
Thank´s for the explanation. Do i have to change R4 and R39 on RX also?

@Sido
I have made some PDF´s to the changes.

Yes, R4 and R39 on the RX board should be the same.

[sido]

Thanks mschmahl for posting the updates.

Some diodes in the RX circuit have a prefix 2Nxxxx. what should they be?

Cheers Sid

[mschmahl]

@ tinkerer
Thank´s for the explanation. Do i have to change R4 and R39 on RX also?

@Sido
I have made some PDF´s to the changes.

[sido]

I have little time at present. My 240 GB storage hard disk crashed and I am packing up my lab for moving. So you will have to exercise patience.

http://www.designspark.com/page/designspark-pcb-home-page

Here you can download the totally free DESIGNSPARK software. Full size, no restrictions.

Tutorials:

http://data.designspark.info/uploads/knowledge-items/designspark-pcb-workshop-teaching-materials-for-universities/DesignSparkPCB_TeachingMaterials_20130211.zip

All the best

Tinkerer

Hi Tinkerer, thanks for posting the link to Diptrace EDS.

As a matter of interest and sorry to all being off topic, I read a post of your's from early 2011 and i gathered that you may have been using Diptrace and now changed over to Designspark. Correct?? and if so why??

I have downloaded Diptrace and trying to learn it.

Cheers Sid

[Tinkerer]

Hi Tinkerer, any chance of posting the updated circuit changes in PDF that have been discussed in the last few posts. I dont have the EDS you guys are referring too.

Once the Moodz UNIPI physical usable PCB and hopefully ideal circuit layout is produced, i want to experiment with your unique designs.
Having wanting to do so for a while.

Thankyou in advance.

Cheers Sid

I have little time at present. My 240 GB storage hard disk crashed and I am packing up my lab for moving. So you will have to exercise patience.

http://www.designspark.com/page/designspark-pcb-home-page

Here you can download the totally free DESIGNSPARK software. Full size, no restrictions.

Tutorials:

http://data.designspark.info/uploads/knowledge-items/designspark-pcb-workshop-teaching-materials-for-universities/DesignSparkPCB_TeachingMaterials_20130211.zip

All the best

Tinkerer

[sido]

Hi Tinkerer, any chance of posting the updated circuit changes in PDF that have been discussed in the last few posts. I dont have the EDS you guys are referring too.

Once the Moodz UNIPI physical usable PCB and hopefully ideal circuit layout is produced, i want to experiment with your unique designs.
Having wanting to do so for a while.

Thankyou in advance.

Cheers Sid

[Tinkerer]

Ah, like always I forget something.

You can change R8 and R16 on the TX&PSU board to 1.5K to increase the pulse voltage range.

[Tinkerer]

@satdaveukSorry i don´t have a pcb layout, only schematics.@tinkererI have changed the RX Schematic as we have discussed it. Can you look around R6 to -5V, R13 to ground (6V)? I think something is wrong now.[ATTACH]23327[/ATTACH]

Let's start with R6 on the TX board. The purpose of R6 and R13 is to serve as damping resistors for the BU coil. The connection is between the TX and BU coils, as you mention above. R6 and R13 also serve as bypass for some of the TX current. In this case, some fine induction balance adjustment can be made.
While we are at the TX schematic, let's look at the PIC PSU, +5V D. This is referenced to Battery ground with Battery +12 input. If we use a LDO, we can also use Bat 6V input, for lower losses. The pulses from the PIC will now have a voltage of about 5V, referenced to Battery ground. When these pulses get to the RX board, to drive the U2 CD4066, they need to be level shifted. The CD4066 needs CMOS logic, that is LOW=3V HIGH=7V We drive the CD4066 with +/-5V, referenced to Bat_6V GND.
C5, 100nF referenced to the voltage divider R6 and R13 should bring the pulse to the desired level. Analog GND is actually 6V, when referenced to Battery ground or 0V.

R13=15k, R6=12k should be OK

Why is the PIC referenced to Battery ground? The PIC is driving the TC4452 Mosfet driver.

The reason I have these mistakes on the schematics, is because I actually use different parts on my test build, but as these are sometimes hard to find or to solder (TSSOT), I changed them on the Simple Basic design to make it simpler and easier to build. Then, sometimes I make a change on the board and forget to change something on the schematic.
Sorry. Thank you for your patience.

[mschmahl]

@satdaveuk

Sorry i don´t have a pcb layout, only schematics.

@tinkerer

I have changed the RX Schematic as we have discussed it. Can you look around R6 to -5V, R13 to ground (6V)? I think something is wrong now.

[satdaveuk]

Hi Tinkerer
Hope all is well
Have you or anybody here made a working pcb layout yet for the non/
motion version of this design, im using either sprint layout or express PCB and would be great full for a copy as im not that good at doing larger circuits myself.
Thanks in advance

[mschmahl]

Thank´s a lot for this calculation.
Only one question i have for building the coil. For controling the balance you have soldered a cable between TX and BU? Is this right?
The legislation for metal detecting in Saxony is very restricted. I had to make a typ of license to search here. I have to get it each year new and have to be in contact with the archeological institut. The license is limited to a district. But it is ok. My oldest found together with the archeologists was a stony hatchet.

[Tinkerer]

Thanks again for the schematic tinkerer.
What batteries should i use? I can buy different one.
For the coil-cable i have AWG12 for TX and BU. It is 3,5mm with isolation (800V rated) 80 meters long. For Rx i have AWG22 http://www.digikey.de/product-detail...B-100-ND/16146 30,5 meter.

Greetings from saxony

Your coil cables are fine. As there are always some differences in wire thickness and bundle thickness, it is good to test the coil when it is ound, so that any differences can be corrected.

Increasing the TX inductance to about 370uH, reduces the coil current(for the battery) a little but keeps the field strength about the same, because of the increase in the number of turns.

OK, here is the information for the 50cm coil.

TX Inner diameter 48cm 18 turns clockwise.

BU inner diameter 29cm 8 turns counter clockwise.

RX inner diameter 29cm 11 turns clockwise, center tap, 11 turns clockwise.

Check out the IB coil thread and see about the balancing and where the pitfalls are.

All the best

Tinkerer

PS. Is the legislation for metal detecting strict in Saxony?