Question on step 6 tp 9 and 10

[godigit1]

Hi,

I Have the sample delay set at 10us but my EFE is running at 14 us on pins TP9 and 10.
Everything is working as it should but both chips are at 14 us should I worry about it matching the 10 us of the sample delay?
Im running a couple old mc14538bcp chips I had, I misplaced the IC's supplied by with my kit. Could they be the culprit?
Thanks You All.

[homefire]

No Idea what your talking about here. What Kit. What Detector ?

[godigit1]

Hi homefire
Thanks for your response .
This is the Minipulse Beach I refer to.
I didnt figure it mattered much since both minipulses have the same timing set up except for the addition of the gain pot .
In the build document it says the EFE sample should be approximately 10us, is 14us acceptable?

[Qiaozhi]

Hi,

I Have the sample delay set at 10us but my EFE is running at 14 us on pins TP9 and 10.
Everything is working as it should but both chips are at 14 us should I worry about it matching the 10 us of the sample delay?
Im running a couple old mc14538bcp chips I had, I misplaced the IC's supplied by with my kit. Could they be the culprit?
Thanks You All.

Hi homefire
Thanks for your response .
This is the Minipulse Beach I refer to.
I didnt figure it mattered much since both minipulses have the same timing set up except for the addition of the gain pot .
In the build document it says the EFE sample should be approximately 10us, is 14us acceptable?

The EFE pulse delay should be around 100us with the R32 (10k) and C18(10nF).
14us is far too low a value.

[godigit1]

Hi Qaiozhi,
Thanks for your response, I havent posted for a while and Im sorry for not being thorough.
My sample delay is 10us (adjusts normally)TP6
My EFE delay puse is running at 103us TP8
Its my EFE sample widths that are off They are both running 14us on test points 9 and 10.
I checked all my resistor and cap values before install and rechecked location. I will put one of my MP rev D boards on the scope and make sure there the same and if not Ill try swaping chips see if that makes any difference.
Thanks for your help.

[Qiaozhi]

Hi Qaiozhi,
Thanks for your response, I havent posted for a while and Im sorry for not being thorough.
My sample delay is 10us (adjusts normally)TP6
My EFE delay puse is running at 103us TP8
Its my EFE sample widths that are off They are both running 14us on test points 9 and 10.
I checked all my resistor and cap values before install and rechecked location. I will put one of my MP rev D boards on the scope and make sure there the same and if not Ill try swaping chips see if that makes any difference.
Thanks for your help.

Are you sure that you're measuring the signals at the correct testpoints?
You've stated that you have a REV-D board, but TP9 is the output of the second integrator stage.

The correct testpoints for REV-D are:

Main sample delay = 22us (TP5)
Secondary sample delay (EFE) = 100us + main sample delay (TP6)
Main sample pulse width = 58us (TP7)
Secondary sample pulse width = 58us (TP8 )

[godigit1]

Hi Qaiozhi,
I am building the MPP Beach Rev E.
I didnt mean to confuse things with mentioning double checking to the Rev D and or swaping out the MC14538s to double check the chips.
I rescoped everything last night and swaped chips, still no change.
My main sample delay = 10 us TP6
EFE = 106us TP8
Main sample pulse width = 14us Tp9
EFE pulse width = 14us tp10
Everything is testing as should except the Sample Pulse widths.
I guess its ok I would only be able to adjust the gain from 14 us to 57 us but it would be nice to hit that 10 Us mark.
Im not that experianced so Ill ask a stupid question is R35 what I would adjust to fix this if not where should I look?
Thanks again for all your help .

[Qiaozhi]

Hi Qaiozhi,
I am building the MPP Beach Rev E.
I didnt mean to confuse things with mentioning double checking to the Rev D and or swaping out the MC14538s to double check the chips.
I rescoped everything last night and swaped chips, still no change.
My main sample delay = 10 us TP6
EFE = 106us TP8
Main sample pulse width = 14us Tp9
EFE pulse width = 14us tp10
Everything is testing as should except the Sample Pulse widths.
I guess its ok I would only be able to adjust the gain from 14 us to 57 us but it would be nice to hit that 10 Us mark.
Im not that experianced so Ill ask a stupid question is R35 what I would adjust to fix this if not where should I look?
Thanks again for all your help .

OK - now I understand.
R35 and C19 set the minimum value for the main and EFE pulses. This should be 4.7k * 2.2nF = 10.34us. However, there are two diodes also in circuit (D10 and D11) that will raise the minimum delay somewhat. If you really want to get the minimum pulse width down to 10us, then you will need to lower the value of R35.

[godigit1]

Qaiozhi thank you for all your help.
I will adjust R35 with a temporary pot to see what I get and replace it back with a 1% Resistor as close to the value as possible.
Im gonna have to wait a couple weeks to do it. I came to Santa Cruz for a Quck remodel. I was hoping to test the Beach here but next time. For now I brought the my trusty Rev D, hopefully Ill find some time to get to the beach.
Thanks again for all the help and the great projects.