You're welcome
Maybe, an AQV212 would be more up to date. But I had never used one of these.
Thanks for the distortion measurement primer. Will try to see if I can replicate it.
And will wait for your small(er) signal switching circuit.
I think Vds > (rail-to-rail voltage)/2 ; clamping diodes or TVS used for protecting
http://hifisonix.com/wordpress/wp-content/uploads/2013/01/Simple_solid_state_relay_Updated.pdf
"You must not use mosfets with a lower Vds breakdown than your absolute maximum rail to rail
supply voltage – they will fail"
http://hifisonix.com/wordpress/wp-content/uploads/2012/08/Speaker-Relay-V1.03.pdf
"As a general point, note that not under any circumstances can the Vds rating of the mosfets
used be exceeded. The devices must be rated to carry the full +- rail voltage, plus some safety
margin."
Bonsai, can you clarify,please ?
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If the amp is ever going to be used in bridged mode and if the rails are +/-50V the MOSFETs must be rated well above 100V, 120V at least.
Don't go overboard though, very high voltage ratings come with high on-resistance.
If amp is never going to be bridged, 60V MOSFETs will prevent either rail getting to the speaker hot terminal. I'd feel safer erring on the side of caution and assume rail-to-rail voltage as the minimum requirement.
Don't go overboard though, very high voltage ratings come with high on-resistance.
If amp is never going to be bridged, 60V MOSFETs will prevent either rail getting to the speaker hot terminal. I'd feel safer erring on the side of caution and assume rail-to-rail voltage as the minimum requirement.
The trick with sensing bridged output is you need two detector circuits sensing voltage referenced to ground. If the speaker relay is designed as a stereo unit it can normally be used to protect a single channel bridged amplifier. Connect one output to each of the amplifier output leads and the ground connection to the supply ground.
General rule of thumb is double the rail voltage for a minimum safe working voltage for the mosfets, even in non-bridged applications. When things go bad in the amplifier it's not always only the amplifier producing the voltages, there is a speaker that is usually recovering from the early onset of a failing amp that can also be producing some voltage.
General rule of thumb is double the rail voltage for a minimum safe working voltage for the mosfets, even in non-bridged applications. When things go bad in the amplifier it's not always only the amplifier producing the voltages, there is a speaker that is usually recovering from the early onset of a failing amp that can also be producing some voltage.
A friend of mine tried this modified circuit (just he leave the overcurrent circuit unpopulated.
The turn on delay function well but the dc detection isn't working,whatever is the value of dc present.
The green led D3(in series)with another led instead of optocoupler remain always on.
Circuit isn't functional even in simulation.
I will post his own pcb later.
Please help.
The turn on delay function well but the dc detection isn't working,whatever is the value of dc present.
The green led D3(in series)with another led instead of optocoupler remain always on.
Circuit isn't functional even in simulation.
I will post his own pcb later.
Please help.
Attachments
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A friend of mine tried this modified circuit (just he leave the overcurrent circuit unpopulated.
The turn on delay function well but the dc detection isn't working,whatever is the value of dc present.
The green led D3(in series)with another led instead of optocoupler remain always on.
Circuit isn't functional even in simulation.
I will post his own pcb later.
Please help.
My SSR works great. Both channels are powered by single +24V auxiliary psu. Check this video. DC thresholds ca -0.5V and +0.6V
YouTube
I guess, you have "ground problem". X1- and X3GND have to be connected in some way.
Hi, those files were modified by manufacturer (pcbway). In Sprint-Layout you can't make oval holes, so I used "tile" function. Original gerbers are here:
ProtectSSR-v2.0-final.zip - Google Drive
ProtectSSR-v2.0-final.zip - Google Drive
Happy New year.
Have some intresting information regarding distortion.
Grabbed what I had in the drawers I used a UPC1237, VOM1271 and TO247 mosfets with RDS on at 0.09 ohm.
Worked ok for 8 ohms raising distortion ~0.002%, but in 4 ohms distortion went up to 0.44% !
Swapped the mosfets to ST TO220 devices. RDS on at 0.004 ohms resulted in significant lower distortion.
With 8 ohms load the difference are hardley measureble, and in 4 ohms it went up ~0.004%.
Have some Toshiba TK72 something on order to, I hope they will work.
BR
//Figge
Have some intresting information regarding distortion.
Grabbed what I had in the drawers I used a UPC1237, VOM1271 and TO247 mosfets with RDS on at 0.09 ohm.
Worked ok for 8 ohms raising distortion ~0.002%, but in 4 ohms distortion went up to 0.44% !
Swapped the mosfets to ST TO220 devices. RDS on at 0.004 ohms resulted in significant lower distortion.
With 8 ohms load the difference are hardley measureble, and in 4 ohms it went up ~0.004%.
Have some Toshiba TK72 something on order to, I hope they will work.
BR
//Figge
Happy new year,
Oh, than I could have problems? What is causing the extra distortion... when the xfmr is near the fet's.
https://www.diyaudio.com/forums/solid-state/318946-ssr-speaker-protection-15.html#post5841649
I haven't actually had the time to investigate the issue too deeply yet (it's on my to do list though). I found this while taking some distortion measurements on the output of an amplifier I built and cured it by relocating the supply section of the protection system. I assume it's due to the gates picking up some AC voltage from the transformer though.
I'm lost... I'm unable to understand what an AC protection can be, so that I don't know where to connect the AC pin to my test amplifier (heavily unbalance in LTSpice).
I understand DC, OC, but not AC. Sorry about that.
It could be the reason why the circuit doesn't work in my simulations. I assumed that the circuit is powered by the amplifier dual mono PSU.
Sorry for the very dumb question.
I understand DC, OC, but not AC. Sorry about that.
It could be the reason why the circuit doesn't work in my simulations. I assumed that the circuit is powered by the amplifier dual mono PSU.
Sorry for the very dumb question.