New Bipolar Boost TX and Front End

[Mdtoday]

35T.

Ok Thanks

[KingJL]

I just discovered that I need to provide some input bias to the THAT1512. It looks as if 5K from each leg to common will suffice and will not upset the damping. That being said the adjustable REF is probably redundant... just set it to 1/2 of the 20 supply. It looks as if using the biasing arrangement for the THAT1512, there is no longer a need to feed the ref to the coil input via the 2Meg resistance.

[Mdtoday]

Ok, yes that would make sense dropping the adjustable REF as long as the 20v is relatively clean.

Are you using a switching regulator to obtain the 20v JL?

cheers

Mdtoday

[KingJL]

Are you using a switching regulator to obtain the 20v JL?

I plan on using MT3608 boost regulator modules (I have 5 of them) to provide both the 5V and the 20V.

[Mdtoday]

Thanks for the info

So all should be fine then with an extra bit of decoupling for 1/2 supply ref

[KingJL]

Thanks for the info

So all should be fine then with an extra bit of decoupling for 1/2 supply ref

That's my feeling... but for the time being, I think I will leave the adustable REF.

BTW: I now have a sim with a THAT1512 model running succesfully.

[Mdtoday]

That's my feeling... but for the time being, I think I will leave the adustable REF.

BTW: I now have a sim with a THAT1512 model running succesfully.

Ok, sounds like a good plan.

Good news on the THAT1512 sim

Looks like you could squeeze the bias resistors in near pin 5 of THAT1512

cheers

Mdtoday

[KingJL]

New versions

I made some changes to accommodate supplying needed bias to the THAT1512 inputs and to remove the R19 path to supply REF to the positive THAT1512 input. All files, schematic, board, BOM, and gerbers have been updated.

[Mdtoday]

I made some changes to accommodate supplying needed bias to the THAT1512 inputs and to remove the R19 path to supply REF to the positive THAT1512 input. All files, schematic, board, BOM, and gerbers have been updated.

Thank you, I had a quick look over and noticed what appears to be a missing foot print.



I'll have another look over later and report if I find anything else

cheers

Mdtoday

[KingJL]

... I had a quick look over and noticed what appears to be a missing foot print...

Not missing... even more hideous... somehow, I had flipped it to the wrong side of the board. So, it ended up with C3 & C19 perfectly overlapping each other.
Please continue checking!!
Corrected files:

[Mdtoday]

Not missing... even more hideous... somehow, I had flipped it to the wrong side of the board. So, it ended up with C3 & C19 perfectly overlapping each other.
Please continue checking!!
Corrected files:

Oops...yeah, it's one of those things isn't it, I'll take another look on Ver.6 and report back.

Cheers

Mdtoday

[Mdtoday]

I thought there was an issue with TX_Coil- via connected to ground, then realised it is isolated, so all looks good

cheers

Mdtoday

[Mdtoday]

Although the design rule check passes, I think maybe the TX_Coil- track at wire pads is a little too close to TX_COIL+




Other than that, it all looks good, I checked footprints against BOM and that looks OK too.

Nice PCB job JL,

cheers

MDtoday

[Mdtoday]

Hi JL,

I had another look over PCB and it looks like the 20v line is going to its plane via a small track and via?



Cheers

Mdtoday

[KingJL]

Gave some more clearance between COIL+ & COIL-. Increased the track width of the 20V input to 0.508mm (there is very little load on the 20V line, but I increased it anyway). A note about clearance: I have the tolerances set to those allowed by JLCPCB. If you use another board shop you may want to revisit the PCB tolerances.

As for the interface board, I added 4 pmod (12 pin) sockets to provide accessibility of all available IO of the Cmod-A7... should be more than enough! This board is a 2 layer board and plugs into the 20 pin header on the bottom of the TX board. I like the way it turned out and I just may make another generic version with a total of 7 pmod (12 pin) sockets without the 20 pin header socket.