A
Anonymous
Guest
I pulled a good one tonight... putting my SandShark back together so I had to reconnect the coil and the headphone wires to the PCB. Got everything wired up, put on the headphones and turned it on... Damn near shattered my eardrums!
After my ears quit ringing I double-checked everything... yup, wired the headphones to the coil pads. Reversed the hookups and everything works fine. Moral: don't put the headphones on until you know it's OK!
Here's the schematic for the SandShark. The coil switch is a 2N6126 PNP with an 80v BVceo and, by George, it breaks down right at 80v. The preamp is a Maxim 410 (hiss-boo). The sampling switches are part of a 4053 triple 2-to-1 mux... don't think I've seen this used before. Everything is PIC controlled (16C73)... other than this, those who know the SMPI will recognize many similarities.
Timing is below. The numbers are microseconds since the last edge. First edge (t=0) is the flyback edge (not the control pulse), second pulse is the main sample switch, third pulse is the reference sample switch. So Tesoro has set their sample delay at 22.5us which seems long. And there's no way to adjust it... even the PIC is surface mount!
- Carl
<PRE>
__
|_______________________
0
___
_____| |________________
+22.5 +21
___
___________________| |__
+116 +21
</PRE>
After my ears quit ringing I double-checked everything... yup, wired the headphones to the coil pads. Reversed the hookups and everything works fine. Moral: don't put the headphones on until you know it's OK!
Here's the schematic for the SandShark. The coil switch is a 2N6126 PNP with an 80v BVceo and, by George, it breaks down right at 80v. The preamp is a Maxim 410 (hiss-boo). The sampling switches are part of a 4053 triple 2-to-1 mux... don't think I've seen this used before. Everything is PIC controlled (16C73)... other than this, those who know the SMPI will recognize many similarities.
Timing is below. The numbers are microseconds since the last edge. First edge (t=0) is the flyback edge (not the control pulse), second pulse is the main sample switch, third pulse is the reference sample switch. So Tesoro has set their sample delay at 22.5us which seems long. And there's no way to adjust it... even the PIC is surface mount!
- Carl
<PRE>
__
|_______________________
0
___
_____| |________________
+22.5 +21
___
___________________| |__
+116 +21
</PRE>