This sounds and looks like a job for an Arduino😀 combine all the above with a Triac Zero crossing AC power control circuit and you have a winner. The programming is super simple. Even I could do it.
Electronic fuse(regressively delayed) is there to protect the amp from short output or transient overdrive, and the rest of protection is to save the loudspeaker from amp fault.
If the protection is triggered, but no fault in the amp then turn off for a minute or so will restart the amp.
I don't like output relay, even special for audio, nor I like MOSFET type relay as it still introduce distortion.
ps. and yes, cap multipliers as main part of that protection enormously improve PSRR.
Last edited:
We can make another thread to do this jobs. 😎
We should consider this protections for hi-fi amplifier, not for PA.
The protections must silent for normal listening and average room temperature and not adding distortion or reduce signal to noise ratio of the amplifier it self.
Sounds like a doable plan, something that has been on my mind for a long time.
Attachments
A new protection thread could start with a discussion on Flow Chart operation to manage the diverse options.
What signals are created for fault detection?
What devices are available for fault protection?
What are the program equations between detection and protection?
MOSFET logic gates can be used with a +/- 15V power supply. The team may find that MOS Logic better matches the modest gating complexity requirements, control voltages, and control currents than a microcontroller. A simple RC delay for soft-start is accurate enough.
What signals are created for fault detection?
What devices are available for fault protection?
What are the program equations between detection and protection?
MOSFET logic gates can be used with a +/- 15V power supply. The team may find that MOS Logic better matches the modest gating complexity requirements, control voltages, and control currents than a microcontroller. A simple RC delay for soft-start is accurate enough.
Attachments
Last edited:
After relay/triac for power ON triggered then delay 500mS for trigger the relay/triac soft start. See http://www.ti.com/lit/an/snaa057b/snaa057b.pdf
for soft start description.
For temperature detection, we can use LM35, but may be difficult to mount. Fan control using PWM for speed controller.
Checked the 2/3/5 pair (all OPS's).
You got it ... just the 5-pair has R101/102 labeling swapped.
R108/109 are correct on all 3.
Copper is correct on all 3.
All 3 OPS's are the same layout except for OP #.
1 labeling error on the "monster". 😱
OS
5-pair screen fixed.
Can't "outsource" this -😱 ... 😀
Spookyamp (leach) labeling fixed , too .. 😱
Also , I decided .... for protection , just switch off the rails using mosfets
and a latching protection circuit - PERIOD. (still have the fuses as failsafe).
Current sense , DC , AC turn-on will all go to the PS board as will the
ta7317 or upc1237. "All-in-one".
PS - I heeded the words of Dadod (possible thd) ...
and with a fault ,totally " killing" the WHOLE amp is the best. (no smoke)
OS
Can't "outsource" this -😱 ... 😀
Spookyamp (leach) labeling fixed , too .. 😱
Also , I decided .... for protection , just switch off the rails using mosfets
and a latching protection circuit - PERIOD. (still have the fuses as failsafe).
Current sense , DC , AC turn-on will all go to the PS board as will the
ta7317 or upc1237. "All-in-one".
PS - I heeded the words of Dadod (possible thd) ...
and with a fault ,totally " killing" the WHOLE amp is the best. (no smoke)
OS
Last edited:
Hi OS, if you are worried about THD with the solid state or speaker relay... can you please add crowbar protection to the output that triggers on DC offset?
I'm worried about damage to the speakers occuring while the rails collapse. Rail switches and output crowbar would be a good solution.
Project 120
I'm worried about damage to the speakers occuring while the rails collapse. Rail switches and output crowbar would be a good solution.
Project 120
I wonder about all the worry about amplifier protection schemes as I have only ever taken out one amplifier, a Parasound, and that was my fault using a new crossover design and having the amp in bridged mode at high volume and the crossover causing an oscillation, a design error on my part. The speakers survived untouched, the output devices did not fair so well.
Otherwise with speakers I have only damaged some while playing at such high levels that I shouldn't have been in the room! A nice burnt voicecoil, but this took two hundred watts on a 6 1/2" cone driver. Other than these two times I have yet to have a catastrophic failure of any kind. What is it that we are expecting to cause this kind of damage or failure in a well built and designed and tested amplifier?
Otherwise with speakers I have only damaged some while playing at such high levels that I shouldn't have been in the room! A nice burnt voicecoil, but this took two hundred watts on a 6 1/2" cone driver. Other than these two times I have yet to have a catastrophic failure of any kind. What is it that we are expecting to cause this kind of damage or failure in a well built and designed and tested amplifier?
When the rail "collapse" , all there is left are the OPS PCB decoupling caps holding
a charge.
When the mosfets shut off , this happens in microseconds. A typical
relay will arc and take milliseconds.
Disconnecting the PS rails (with FET's) would be MUCH faster than any mechanical relay's action-
plus the discharge of the local decoupling would be nearly instantaneous.
Also, you would save what's left of the amp AND your speaker.
Read here... A DC Fault Protection Circuit for Audio Amplifiers
(I'm still reading ...)
PS - one more mosfet (crowbar) to short the OP to ground would be cool.
Fire all 3 off simultaneously.
OS
Last edited:
Kids are easier to handle than drunk people, you use fear with children! Those wires can kill you seems to work pretty good!
OS, are you going to redesign the 3x OPS boards with rail cut circuits or do you plan to offer this on a seperate daughterboard.
Triac soft start to the mains power transformer has been used on Pro Amps for years, & is very successful 😉 Another way it's been done, is a with a circa 50W 0.5R resistor in series with the Tranny, which gets shorted out with a power relay after a delay.
That upc1237 looks the ticket though 🙂
Bonsai's solid state output protection "appears" to be very well worth exploring.
Also a mosfet, or bipolar, DC supply cutoff seems like a good idea too !
That upc1237 looks the ticket though 🙂
Bonsai's solid state output protection "appears" to be very well worth exploring.
Also a mosfet, or bipolar, DC supply cutoff seems like a good idea too !