Preamp

[green]

No problem, at the time of sampling the avalanche is long gone together with its noise.

That has been my thought, but I'm not certain it's correct. Need to see if I can see a difference in post amp output noise with and without the snubber.

[green]

I'm thinking Teleno's amp needs to be capacitor coupled to the integrator. I've been direct coupling with my test circuit. Wondering what the advantages and disadvantages are. EF cancelling works because the two samples are the same. With capacitor coupling they won't be, is that a problem?

[6666]

I have posted my novel GB scheme in another thread, should be tested in Aussie goldfields. If it works then gain shouldn't be a problem.

Could you please post a link to it ? or a clue where to find it . thanks

[Old cart]

I'm thinking Teleno's amp needs to be capacitor coupled to the integrator. I've been direct coupling with my test circuit. Wondering what the advantages and disadvantages are. EF cancelling works because the two samples are the same. With capacitor coupling they won't be, is that a problem?

Only if the cap decays during the TX off time. If it is large enough it should not be problem

[Teleno]

I'm thinking Teleno's amp needs to be capacitor coupled to the integrator. I've been direct coupling with my test circuit. Wondering what the advantages and disadvantages are. EF cancelling works because the two samples are the same. With capacitor coupling they won't be, is that a problem?

Surfmaster is already capacior coupled, so EF cancelling must be iffy at best.

Could you please post a link to it ?

This is it: http://www.geotech1.com/forums/showt...mit-time/page3

[6666]

The typical surf cct uses 100n cap between preamp and int

[Teleno]

The typical surf cct uses 100n cap between preamp and int

Yes, it's 100n in series with a 10K resistor. The time constant is 1ms.

The late sample (EF) is taken at about 240us after the main sample. This means the late EF is 20% lower than the early EF (it decays to 80% of the initial value after 240us). It can be compensated by a gain coefficient, though.

A better solution is to use a preamp (gain 10 - 20) and couple it capacitively to a JFET-input Op-Amp which, in turn, is DC coupled tot he integrator. In this case you can use C = 100n and R=1M for a time constant of 100ms. The decay after 240us is a mere 0.3%.

[Sean_Goddard]

Alright I'll do the maths and the electronics design, you do the PCB layout and prototyping. Deal?

I can do the programming as well unless we have a more experienced volunteer.

Sounds like a "goer" to me. As soon as you have done the schematic I'll start on the PCB. Now, what design package are we going to use as we need a commonality. Has anyone tried DesignSpark from RS? Mechanical AND now Electrical too (that was my idea).

http://www.rs-online.com/designspark/electronics/

It's FULLY fledged and FREE! Or if you google "sonsivri" you can get any full version CAD package. MultiSim and Ultiboard etc, Eagle, Sprint and even Protel, but the setup for that takes about three hours. Let me know.

[Qiaozhi]

It's FULLY fledged and FREE! Or if you google "sonsivri" you can get any full version CAD package. MultiSim and Ultiboard etc, Eagle, Sprint and even Protel, but the setup for that takes about three hours. Let me know.

Sean - I have registered a request to join the Sonsivri forum, but it requires someone to actually invite me to join for free. Otherwise it costs $20.
Please can you go to the Invitation Request section of their site and click on "Invite this person"?
Thanks.

[Teleno]

Sounds like a "goer" to me. As soon as you have done the schematic I'll start on the PCB. Now, what design package are we going to use as we need a commonality. Has anyone tried DesignSpark from RS? Mechanical AND now Electrical too (that was my idea).

http://www.rs-online.com/designspark/electronics/

It's FULLY fledged and FREE! Or if you google "sonsivri" you can get any full version CAD package. MultiSim and Ultiboard etc, Eagle, Sprint and even Protel, but the setup for that takes about three hours. Let me know.

My PC runs on Linux and I've got Eagle (free limited version) for schematics and PCB. Not much, really. Eventually I can use a second PC with Windows Vista but I'd have to install the necessary CAD packages from scratch. Anyone of your preference would do, I can adapt.


I would need the invite for Sonsivri too. Here's my request: http://www.sonsivri.to/forum/index.p...=61849.new#new

[Sean_Goddard]

Alas it is one forum where the rules are VERY harsh. I havn't been on there for over a year so they booted me even thought I was a paying member.

BE CAREFUL, the admin there are VERY quick to punish for infgringements. DO direct downloads, NO files on the forum, links ONLY. They have all sorts on there, I've even seen Mentor somewhere!

I will try to get back on there, I was Sidley65.

Have just re-applied.

Teleno, what Linux Distro are you running? I've used RoboLinux (brilliant). You could VM ware a Pc onto it and run Proteus (simulations too) which I just happen to have as a stand alone wink, wink.

[green]

Is the plan, one board for the whole detector or maybe 2,3 or 4 sections with a board for each section?

[Teleno]

ATeleno, what Linux Distro are you running? I've used RoboLinux (brilliant). You could VM ware a Pc onto it and run Proteus (simulations too) which I just happen to have as a stand alone wink, wink.

I'm running an older Ubuntu with wine and VMware. Wine failed to install DesignSpark, can you suggest other free alternatives?

Edit: I've successfully installed ExpressPCB and ExpressSCH http://www.expresspcb.com/free-cad-software

Is the plan, one board for the whole detector or maybe 2,3 or 4 sections with a board for each section?

One board will do since the component count is low. An off the shelf (I2C) LCD+buttons will serve as user interface.

[Qiaozhi]

Alas it is one forum where the rules are VERY harsh. I havn't been on there for over a year so they booted me even thought I was a paying member.

BE CAREFUL, the admin there are VERY quick to punish for infgringements. DO direct downloads, NO files on the forum, links ONLY. They have all sorts on there, I've even seen Mentor somewhere!

I will try to get back on there, I was Sidley65.

Have just re-applied.

A member from this forum invited me to Sonsivri, so I'm now registered. Yes, I've read the rules, and they're very strict.

Teleno, what Linux Distro are you running? I've used RoboLinux (brilliant). You could VM ware a Pc onto it and run Proteus (simulations too) which I just happen to have as a stand alone wink, wink.

For the record, I'm using Ubuntu 12.04, with Kernel Linux 3.2.0-97-generic-pae, GNOME 3.4.2, and Unity as the graphical shell.
To start with I didn't like Unity much, but now I've got accustomed to it.

[Sean_Goddard]

Is the plan, one board for the whole detector or maybe 2,3 or 4 sections with a board for each section?

Two boards, one for TX one for RX better noie isolation that way, to PLENTY of filtering on the Rx board.

Teleno, Express looks just fine. I didn't want to have to use another package, have you also tried DIPTRACE? http://diptrace.com/

Great 3D with it too. Limited yes, but it we do this as two boards then I can still do this as I have the full version. there is also a LINUX version - WOOT!!