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I can't remember now -- I see my Photoshop has an export to PDF option so I may have converted from bitmap that way. I also have a "PDF" printer driver, could have been that, or even NitroPDF which I have.
I notice on eduardo's schematic the unused LM358 is "tied off" using several resistors.
I looked into this and became convinced that you can tie off the op amp without needing resistors. See photos below for comparison.
However, I'm interested if others have opinion on this. It seems useful to simplify our PCBs if we can get rid of any unnecessary parts.
-SB
Sorry about that.. I wasn't focused on that part of the circuit at all so didn't even look at it!
Thanks for picking up where I left off and completing the schematic. I left the component IDs blank on purpose hoping that someone could make a suggestion.
Hopefully, Andy can make use of the documentation and provide it along with his TGSL kits at his online store.
Some great work by Don and others, most beyond me at the moment, but I'm trying to understand it - looking forward to the troubleshooting section, thats the one I always use most
My contribution is to recycle some recent sales money - I have for the rest of June reduced pcbs by 50% and kits are reduced to just £21 GBP
Sorry about that.. I wasn't focused on that part of the circuit at all so didn't even look at it!
Don
I assume eduardo's PCB has the resistors (haven't checked myself). Just wondering if anyone else gets rid of them (I do on my PCBs, but doesn't mean it's good), and if it is good practice to use the simpler way to tie off the unused op amp.
If so, it would give eduardo a little more space to work with on the PCB, and a simpler PCB to build. Just a suggestion.
I assume eduardo's PCB has the resistors (haven't checked myself). Just wondering if anyone else gets rid of them (I do on my PCBs, but doesn't mean it's good), and if it is good practice to use the simpler way to tie off the unused op amp.
If so, it would give eduardo a little more space to work with on the PCB, and a simpler PCB to build. Just a suggestion.
This is the one I use -- note the resistors are not necessary for TGS due to dual supply, just ground the non-inverting input.
-SB
The circuit in Figure 1 satisfies both conditions.
If the circuit has dual supplies, ±3V for example, the two resistors are not necessary and simply grounding the non-inverting terminal is sufficient. Additionally, the non-inverting terminal can be connected to another voltage elsewhere in the circuit that is within the input common-mode voltage range of the device, thereby eliminating the need for the two resistors in Figure 1.
Figure 1. A properly terminated uncommitted op amp. The input common-mode range is satisfied and the output is within the output voltage swing range.
as previously stated, I built TGS, which worked ,but I had trouble with notch filter. I was going to build TGSL, but I settled on TGSL edu, I now get 30 cm depth. I went out hunting a 100 year old high school playfield and found a canadian quarter and some pennies. To my amazement, I found razor sharp discrimination between silver and aluminum. complete discrimination of large steel, but strangely I was hitting old magnetic sensitive beer bottlecaps. Here are some pics of my latest vacuum formed coils. If it is helpful to anyone, I found that you need to get the abs hot enough that its sagging almost to the bottom of the oven, carefully watch it! then you place the frame on the vacuum box, and you will here the rPMs of the shopvac go up, and you will get good detail on your coil shell. On nulling the coil, I hold the top coil while watching the oscilloscope, then drop dollar store glue gun glue on coil points, I then use dollar store $1. epoxy to secure coils further. Then use 24 hr epoxy to fill the coilshell with no movement.
Finally I got a good discriminating reliable detector. I searched the TSGL posts. and saw that the original Tesoro patent allowed bottlecaps? anyone???
as previously stated, I built TGS, which worked ,but I had trouble with notch filter. I was going to build TGSL, but I settled on TGSL edu, I now get 30 cm depth. I went out hunting a 100 year old high school playfield and found a canadian quarter and some pennies. To my amazement, I found razor sharp discrimination between silver and aluminum. complete discrimination of large steel, but strangely I was hitting old magnetic sensitive beer bottlecaps. Here are some pics of my latest vacuum formed coils. If it is helpful to anyone, I found that you need to get the abs hot enough that its sagging almost to the bottom of the oven, carefully watch it! then you place the frame on the vacuum box, and you will here the rPMs of the shopvac go up, and you will get good detail on your coil shell. On nulling the coil, I hold the top coil while watching the oscilloscope, then drop dollar store glue gun glue on coil points, I then use dollar store $1. epoxy to secure coils further. Then use 24 hr epoxy to fill the coilshell with no movement.
Finally I got a good discriminating reliable detector. I searched the TSGL posts. and saw that the original Tesoro patent allowed bottlecaps? anyone???
Excellent job!
Yes, rusty bottlecaps seem to be able to fool Tesoro, maybe all, MDs. I don't know why.
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