I always assumed it was like shoot through in Mosfets. There was likely a pretty good voltage spike when the transistors blew that took out the Mosfet on the relay.
1KVA warm !
even a 500W quartz halogen has little effect on thosesecondaries !!
I knew the slew was industrial , but not "military" ...
Regular amps not oscillating , playing pretty loud - my 1kva does not get warm
at all.
OS
Actually, though the MOSFETs in the relay are mechanically in series, electrically speaking it is really just one or the other. When the relay is 'open' the voltage applied appears across one or the other MOSFET depending on polarity. This is due the the fact that a MOFFET has a 'parasitic' body diode that forward biases leaving the other MOSFET to block the full voltage.
So long as catching diodes are installed the relay should work for any reasonable DIY build with no problem. If you go full paranoia you would really go for 200V or higher Vds devices, at the expense of Rds specification. That is the beauty of the devices chosen, the Rds specification is really good for a 100V device.
Yes you are right again. Even at 100 volts these should be good for just about any amp though.
The test was a success anyway. The relays run cool. I wasn't able to measure any voltage drop across them in operation. The catching diode in the device withstood current better than the mosfet itself and the mosfet went open circuit on failure. All good.
Can you think of anything else I should test on them? I never actually tested their reaction time in circuit. That would likely be good to know.
Yes you are right again. Even at 100 volts these should be good for just about any amp though.
The test was a success anyway. The relays run cool. I wasn't able to measure any voltage drop across them in operation. The catching diode in the device withstood current better than the mosfet itself and the mosfet went open circuit on failure. All good.
Can you think of anything else I should test on them? I never actually tested their reaction time in circuit. That would likely be good to know.
The analog sensors and micro would be slower than the actual mosfet "action".
I'm glad I did not have speakers hooked up tonight. Put a cap in backwards
... one NJW0302 rose in current very rapidly after I fixed the OPS.
It actually had a bubble of copper coming out the bottom of the slug , it was damaged and about to runaway.
The 4 remaining pairs are working good for hours at high bias. Sucks .. Ill
have to restuff one OPS with my mt-100 sankens.
I'll have to fast-track this protection board , an idiot like me really needs it !
OS
FAST TRACK ....
yeah , fast track my butt !
This stuff is small. I can actually solder it with very good results , but have
to test each part (can't see them ! )
Magnifying glass is essential here.
Questions -
1- resistor network has 9 pins , pcb has 8 holes ???
2 - the 1uF tantalum cap is the ATmega 5V reg decoupling ?
3- the (real) small dipped ceramics are the crystal caps , 22pf?
OS
yeah , fast track my butt !
This stuff is small. I can actually solder it with very good results , but have
to test each part (can't see them ! )
Magnifying glass is essential here.
Questions -
1- resistor network has 9 pins , pcb has 8 holes ???
2 - the 1uF tantalum cap is the ATmega 5V reg decoupling ?
3- the (real) small dipped ceramics are the crystal caps , 22pf?
OS
1 Chop off pin 9. Pin 8 isn't needed either. Pin 1 is the common pin.
2 That should be a .1 unless I sent the wrong one. Yes it's for Atmega decoupling.
3 Yes those are the crystal caps.
Thank you , Jeff.
I have most of the resistors in.
The U4/5 are not on the BOM , but I know from the big
board "what's what" (schema also shows U4/5/7).
The tantalum is "104" (I could not see it before) - .1u ! cool...
The resistor network was the only truly unknown. (could not read it).
I'm doing 2 boards , as these are difficult . Iron is sharpened to a needle
point - hand as steady as a surgeon.
On the ATmega end - perfect. UNO is fast to load
my latest "V8 script" (I'm using "D12/13" now).
OS
I have most of the resistors in.
The U4/5 are not on the BOM , but I know from the big
board "what's what" (schema also shows U4/5/7).
The tantalum is "104" (I could not see it before) - .1u ! cool...
The resistor network was the only truly unknown. (could not read it).
I'm doing 2 boards , as these are difficult . Iron is sharpened to a needle
point - hand as steady as a surgeon.
On the ATmega end - perfect. UNO is fast to load
my latest "V8 script" (I'm using "D12/13" now).
OS
Oops... everybody's building 21-st century boards?
Could be. I hope everyone I sent sample boards to got some before they ran out. I'd like to hear what they think of them.
Yes , thanks to you.Cool stuff
Did you know unused digital pins on the ATmega can cause possible errata ?
Luckily this can be taken care of through script.. Assign a name to any
un -used digital pin and either set it as a output (low or high) , or
as an input -
To do nothing , the pin(s) default to a high Z input "floating" - susceptible
to noise.
Jeff's new board has D12/D13. I'm using D13 as "faultLED" , taking over
any alarms to flash the red half of my bicolor LED.
Original "powerLED" goes high on fault now.
D12 can be a capacitive input - ahhh . to touch a sensor to start or
shutdown - that's 21'st century !
OS
D12 and D13 are buffered through this ULN2003 so they can only be outputs. Those outputs are held low by the 2003 too.
That sucks. (for my input idea)
I guess the red led will like it .... I'll flash it real bright.
You could of just left em "raw" - 40ma unbuffered (leds) or
"scriptable" input modes with no components.
OS