Hello everyone,
Following the sudden death of my Sherwood R965, which I was unable to repair, I decided to build an ESP P101 Mosfets amplifier.
I'm going to start with two channels, and will probably add three more later.
So I bought a set of boards from Rod, including:
2x P101c Power amplifier
1x P39c Soft start
1x P33b Loudspeaker protection
2x P245a Mosfet relay
I will reuse the Sherwood R965's case and power supply (600W, +/-56V, 2x27000 uF).
Regarding the P245a (mosfet relay), Rod recommends several references, but I already have components that seem suitable, although I don't have the expertise to be certain.
The mosfets I have are : CSD19536KCS from Texas Instruments
Will they be suitable for this application ?
Regarding the P101c, Rod mainly recommends the ECX10N20 / ECX10P20 references, but these components are difficult to find and obsolete according to the manufacturer, who instead recommends the ECX10N20-W6 / ECX10P20-W6 models.
Again, I assume they are suitable, but I want to be sure...
Thanks in advance to anyone who tries to help me.
Following the sudden death of my Sherwood R965, which I was unable to repair, I decided to build an ESP P101 Mosfets amplifier.
I'm going to start with two channels, and will probably add three more later.
So I bought a set of boards from Rod, including:
2x P101c Power amplifier
1x P39c Soft start
1x P33b Loudspeaker protection
2x P245a Mosfet relay
I will reuse the Sherwood R965's case and power supply (600W, +/-56V, 2x27000 uF).
Regarding the P245a (mosfet relay), Rod recommends several references, but I already have components that seem suitable, although I don't have the expertise to be certain.
The mosfets I have are : CSD19536KCS from Texas Instruments
Will they be suitable for this application ?
Regarding the P101c, Rod mainly recommends the ECX10N20 / ECX10P20 references, but these components are difficult to find and obsolete according to the manufacturer, who instead recommends the ECX10N20-W6 / ECX10P20-W6 models.
Again, I assume they are suitable, but I want to be sure...
Thanks in advance to anyone who tries to help me.
ECX10N20-W6 is most probably the same as ECX10N20.
You should be able to use them in the circuit.
You should be able to use them in the circuit.
Same part. They moved from a 4” wafer to a 6” wafer in the manufacturing process. But the resulting part is the same.
https://us.profusion.uk/media/assets/product/documents/EXICON_PCN5.pdf
https://us.profusion.uk/media/assets/product/documents/EXICON_PCN5.pdf
Sounds good, thank you both.
Regarding the mosfet selection for P245a, I’ve carefully read all the designer's comments:
"The MOSFET's voltage rating needs to be at least 10% (preferably 20%) higher than the maximum voltage expected.
Normally, you would choose MOSFETs with the lowest possible RDS-On to minimise power dissipation.
For loudspeaker protection and similar tasks, few amps run at more than ±100V, so any of the lower voltage types will suffice - depending on current of course."
Considering this, the CSD19536KCS are perfectly adequate as loudspeaker protection relay.
Regarding the mosfet selection for P245a, I’ve carefully read all the designer's comments:
"The MOSFET's voltage rating needs to be at least 10% (preferably 20%) higher than the maximum voltage expected.
Normally, you would choose MOSFETs with the lowest possible RDS-On to minimise power dissipation.
For loudspeaker protection and similar tasks, few amps run at more than ±100V, so any of the lower voltage types will suffice - depending on current of course."
Considering this, the CSD19536KCS are perfectly adequate as loudspeaker protection relay.
I also have a question about the power supply.
I drew a diagram of the power supply I have.
It's not what I plan to build, but what I salvaged from my broken amplifier.
I compared it to the power supply diagram provided by Rod and noticed that there are no components to discharge the two 27mF capacitors after the device is completely turned off.
I'm not sure if this is useful, or if the capacitors will discharge ‘naturally’ in all the device's circuits when it is turned off.
If it is useful or necessary, I was thinking of adding two 10kOhms 0.5W resistors (see image).
What do you think ?
I drew a diagram of the power supply I have.
It's not what I plan to build, but what I salvaged from my broken amplifier.
I compared it to the power supply diagram provided by Rod and noticed that there are no components to discharge the two 27mF capacitors after the device is completely turned off.
I'm not sure if this is useful, or if the capacitors will discharge ‘naturally’ in all the device's circuits when it is turned off.
If it is useful or necessary, I was thinking of adding two 10kOhms 0.5W resistors (see image).
What do you think ?
This is not trivial, since 50V or more is considered potentially fatal, and those big caps hold a lot of charge.
These resistors just help drain the large caps when the amp is turned off. At 56V a 10K resistor draws 5.6mA. And 5.6mA at 56V = .3136W. So yes, .5W is cutting it a little close. Alternatively, a 22K resistor would work as well. It drops the wattage to .1423W so a .5W resistor would be fine. But the time it takes to discharge your caps double.
No need for despair as the MOSFETs under normal idle current drains the caps withing a few seconds when the amp is turned off. A resistor across a cap is merely a safety feature when you tinker. 🙂
No need for despair as the MOSFETs under normal idle current drains the caps withing a few seconds when the amp is turned off. A resistor across a cap is merely a safety feature when you tinker. 🙂
I like to add a LED is series with the resistor. Adds a visual reminder that the caps are still charged.
Still waiting for my printed circuit boards, I'm biding my time by purchasing the necessary components and accessories.
I would like to know if the ceramic insulators for TO-220 cases found on Aliexpress are a good alternative to the mica sheets that are traditionally used.
I assume that these ceramic sheets must also be used with thermal paste.
https://fr.aliexpress.com/item/1005004937964628.html
I find mica fragile and difficult to handle, but if it is still the best solution currently available, I will make do with it.
I would like to know if the ceramic insulators for TO-220 cases found on Aliexpress are a good alternative to the mica sheets that are traditionally used.
I assume that these ceramic sheets must also be used with thermal paste.
https://fr.aliexpress.com/item/1005004937964628.html
I find mica fragile and difficult to handle, but if it is still the best solution currently available, I will make do with it.
I use Aluminum Oxide Ceramic insulators and have not had problems. I've gotten them from the usual suppliers like Mouser or DigiKey. You do need to use thermal paste with them.
If you do use them, they are prone to cracking if overtightened, so you need to be careful.
If you do use them, they are prone to cracking if overtightened, so you need to be careful.