New Bipolar Boost TX and Front End

[KingJL]

Excellent, I will see what I can find over here...

I think the type J (also known as type 75) core material (ui of 5000) with the size about the same as the ones identified will work fine.

I might also solder in some good quality pcb sockets into the transformer pads. That will make things a little better for testing.

That is a superb idea!

[KingJL]

I think the type J (also known as type 75) core material (ui of 5000) ...

As near as I can tell, even though some suppliers list type 75/J, the type 75 only has a ui of ~3000 ( I think I have seen 1 spec that listed it at 3500)... a little short of 5000!

[KingJL]

I will rewind the transformers tomorrow and measure the gate voltages again but I do see an improvement with just reducing the windings back to 4.

I have done some checking and it is safe to make R22, R23, R28, R29, R32, R33, R37, and R38 zero ohm jumpers instead of 1 ohm resistors. That should also help bring up the voltage a little.

[Mdtoday]

I have done some checking and it is safe to make R22, R23, R28, R29, R32, R33, R37, and R38 zero ohm jumpers instead of 1 ohm resistors. That should also help bring up the voltage a little.

Ok, I'll swap them out then and test, thanks.

[Mdtoday]

As near as I can tell, even though some suppliers list type 75/J, the type 75 only has a ui of ~3000 ( I think I have seen 1 spec that listed it at 3500)... a little short of 5000!

Ok,will be mindful of double checking the specs before proceding

[Mdtoday]

I think the ones we have are too small to try and get the total windings needed. A little larger will also make mounting in the currently spaced mounting holes easier also. When we get them as we need them, I think we need some sort of potting (a gel or flexible type... not solid) to support them. You wouldn't believe it but they will fail from micro vibrations caused by their use that will work harden the copper and will lead micro breaks causing increased resitance in the windings. There are some flexible conformal coatings out there.

I agree, they are a bit of a squeeze for mounting. Latex may work well or non acetic flow-able silicone, like you say, there are a number of flexible potting compounds available.

[Mdtoday]

@JL, Here is the Windows 64 bit driver used for Prolific based USB to TTL serial converters.

Profilic_Win8_x64_x86.zip

[KingJL]

Ok, I'll swap them out then and test, thanks.

This is approximately what we are shooting for measured at either Boost_A_G to gnd or Boost_B_G to gnd. We are looking for a minimum peak of 15V... preferably 20V (gives a 10v -15V signal between gate and source).

[Mdtoday]

This is approximately what we are shooting for measured at either Boost_A_G to gnd or Boost_B_G to gnd. We are looking for a minimum peak of 15V... preferably 20V (gives a 10v -15V signal between gate and source).

This is what we have. Yellow trace is Boost_B_G measured at gate of M1, Blue trace is Boost_A_G measured at gate of M3 to Gnd.



I can't find my differential probes at the moment, when I do, I will connect coil take some measurements

[KingJL]

This is what we have. Yellow trace is Boost_B_G measured at gate of M1, Blue trace is Boost_A_G measured at gate of M3 to Gnd.

[ATTACH]48490[/ATTACH]

I can't find my differential probes at the moment, when I do, I will connect coil take some measurements

Things are looking much better (looks like 100% improvement over previous boost signal waveforms)... it looks like Boost_B_G is 9-10 V drive and Boost_A_G is ~11V drive. But it also looks like the total yellow trace is about 85% of the blue trace overall, like there is a missmatch of the channel inputs. If that is the case, then they both might be meeting the minimum 10V drive (actually 9V will work well enough to progress on with testing and we can improve that with new inductors when we get them ready). But I think the drive is now high enough to see what we get for TX.

[KingJL]

@Mdtoday, do you have probe points for M6_G and M7_G?

[Mdtoday]

Things are looking much better... it looks like Boost_B_G is 9-10 V drive and Boost_A_G is ~11V drive. But it also looks like the total yellow trace is about 85% of the blue trace overall, like there is a missmatch of the channel inputs. If that is the case, then they both might be meeting the minimum 10V drive (actually 9V will work well enough to progress on with testing and we can improve that with new inductors when we get them ready). But I think the drive is now high enough to see what we get for TX.

In fact I have just updated the firmware of the DSO and did a calibration, the mismatch has just presented itself...so I will investigate that as it is on channel 4 too and yet channel 1 and 3 are near identical..

This is what I get on channel one for both gate drives, So yes both the same

[KingJL]

In fact I have just updated the firmware of the DSO and did a calibration, the mismatch has just presented itself...so I will investigate that as it is on channel 4 too and yet channel 1 and 3 are near identical..

This is what I get on channel one for both gate drives, So yes both the same

[ATTACH]48491[/ATTACH]

I would like to see the drive a little stronger, but like I said, we can address that with better pulse transformers later. I think the drive as it is is enough to drive the TX. The one that might concern me would be the M6 and M7 drives. Those are on for such a long time the droop might get down to the Vth with the drive starting out at ~9.5V.

[Mdtoday]

I would like to see the drive a little stronger, but like I said, we can address that with better pulse transformers later. I think the drive as it is is enough to drive the TX. The one that might concern me would be the M6 and M7 drives. Those are on for such a long time the droop might get down to the Vth with the drive starting out at ~9.5V.

Yes, I think I might now go and rewind the primary of one transformer with .63mm diam wire see if we can squeeze a little more out of it.

Here is the gate drive on M2

[KingJL]

... Here is the gate drive on M2... [ATTACH]48492[/ATTACH]

That looks perfect!!