Hi ,
I'am building the AV800 amplifier ( from Holton ) and i want to add a clipping indicator , a speaker protection ( maybe i will use uPC1237 ) , soft start , a signal leg ( like on the QSC amplifiers and other ) .
With the clipping indicator the problem was that my amplifier use 90V ( 2 x 65V AC and 2500 W supply ) ... the clipping indicator from http://sound.westhost.com/project23.htm it's for 70V maximum .. and on the last table i don't know the formula to calculate the resistor for 90V . Anyone know a better solution ?
Another problem was the short circuit protection , I know that the uPC1237 can do this but i don't know how ...
Thanks .
I'am building the AV800 amplifier ( from Holton ) and i want to add a clipping indicator , a speaker protection ( maybe i will use uPC1237 ) , soft start , a signal leg ( like on the QSC amplifiers and other ) .
With the clipping indicator the problem was that my amplifier use 90V ( 2 x 65V AC and 2500 W supply ) ... the clipping indicator from http://sound.westhost.com/project23.htm it's for 70V maximum .. and on the last table i don't know the formula to calculate the resistor for 90V . Anyone know a better solution ?
Another problem was the short circuit protection , I know that the uPC1237 can do this but i don't know how ...
Thanks .
Rod Elliott sayed : The transistors must be rated for the supply voltage. For most systems (less than +/- 70V) BC639 - NPN (Q2) and BC640 - PNP (Q1) will work happily. They are over the top in power and current ratings, but we need the 80V rating. I do not know of suitable (readily available) devices for use at higher voltages.
I searched over the net for other transistors but i couldn't find ....
I searched over the net for other transistors but i couldn't find ....
Thanks !!! The problem with the clipping indicator is solved .
Now only the speaker protection circuit remain . I found uPC1237 , a speaker protection IC but i don't know how good it is . Maybe someone know a better protection circuit with short circuit protection ( 4 Ohm is the minimum impedance for this amplifier , it can support 2 ohm only if the supply voltage is reduced ) . As i found in professional amplifiers after a shot circuit or overload is produced the amplifier go in protect mode and after 5 seconds is operating again .
Another thing i want to integrate in this amplifier is a signal led ( as found in professional amplifier , when signal is detected a led blink such as a VU METER ) . I don't want a full VU METER , only a single led .
Softstart is OK , i will use the schematic on Rod Elliott site .
If anyone think that i should integrate anything alse than soft start , clipping indicator , speaker protection , short circuit protection , thermal protection , signal led in this amplifier let me know .
Thanks .
Now only the speaker protection circuit remain . I found uPC1237 , a speaker protection IC but i don't know how good it is . Maybe someone know a better protection circuit with short circuit protection ( 4 Ohm is the minimum impedance for this amplifier , it can support 2 ohm only if the supply voltage is reduced ) . As i found in professional amplifiers after a shot circuit or overload is produced the amplifier go in protect mode and after 5 seconds is operating again .
Another thing i want to integrate in this amplifier is a signal led ( as found in professional amplifier , when signal is detected a led blink such as a VU METER ) . I don't want a full VU METER , only a single led .
Softstart is OK , i will use the schematic on Rod Elliott site .
If anyone think that i should integrate anything alse than soft start , clipping indicator , speaker protection , short circuit protection , thermal protection , signal led in this amplifier let me know .
Thanks .
Hi Dark,
you can change the thermal protection to latching thermal shutdown.
Try adding a DC block and interference suppression to the input of the transformer.
What about an orange LED flashing @-3db and the red LED @-1db or -0.5db?
Add a delay (50mS) on the LED so you can see the flash.
you can change the thermal protection to latching thermal shutdown.
Try adding a DC block and interference suppression to the input of the transformer.
What about an orange LED flashing @-3db and the red LED @-1db or -0.5db?
Add a delay (50mS) on the LED so you can see the flash.
richie00boy said:Maybe 2N5401 and 2N5551 could be used? They have reversed pinout but as no PCB layout is done it shouldn't matter.
Or MPSA42/92 (MPSA43/93)...
Now I'am building this : http://sound.westhost.com/project39.htm , i have another problem , i can't find the mosfet from the schematic at any local supplyers (
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