Hi Salas,
Off topic (kind of) this, but I know I can find you here:
I just got the R-core transformer for my TDA1541A DAC.
It is 20v and 12v 12v 12v 220VAC to achieve -15v and 5v -5v 5v DC
Because of my countries 240Vac (nominal) system, the results are quite high.
I am getting 23.5v and 14.4v 14.3v 14.2v from the leads, which is high even for the 220/240 discrepancy. I was expecting 21.8v and 13.1v, 13.1v, 13.1v
After rectification using 4x Fairchild Stealth Diodes per channel and 10x Panasonic FC 2200uF caps, and a WIMA 0.1uF decoupling cap per channel, I am getting DC of 31.4v 18.7v 18.5v 18.3v,
so to achieve 15v 5v 5v 5v will mean a LOT of voltage lost in the shunt regulation. I haven't hooked them up to the shunt regs yet, as I still need some small bolts for the mosfet to heatsink connection
I am wondering if I will be OK with these small sinks and the planned 10R 5W current resistor, as there is going to be a lot of voltage wasted here. I am thinking 22R might make more sense, or bigger sinks, or both. Any thoughts?
Off topic (kind of) this, but I know I can find you here:
I just got the R-core transformer for my TDA1541A DAC.
It is 20v and 12v 12v 12v 220VAC to achieve -15v and 5v -5v 5v DC
Because of my countries 240Vac (nominal) system, the results are quite high.
I am getting 23.5v and 14.4v 14.3v 14.2v from the leads, which is high even for the 220/240 discrepancy. I was expecting 21.8v and 13.1v, 13.1v, 13.1v
After rectification using 4x Fairchild Stealth Diodes per channel and 10x Panasonic FC 2200uF caps, and a WIMA 0.1uF decoupling cap per channel, I am getting DC of 31.4v 18.7v 18.5v 18.3v,
so to achieve 15v 5v 5v 5v will mean a LOT of voltage lost in the shunt regulation. I haven't hooked them up to the shunt regs yet, as I still need some small bolts for the mosfet to heatsink connection I am wondering if I will be OK with these small sinks and the planned 10R 5W current resistor, as there is going to be a lot of voltage wasted here. I am thinking 22R might make more sense, or bigger sinks, or both. Any thoughts?
I've got these wakefield heatsinks (287-1abe) from my other dcb1 build that I didn't use.
I'm hoping these would keep the mosfets cool enough - they're rated at 56°C @ 4W.
Here's the link to mouser...
567-287-1ABE
I do believe I would need insulators between the heatsink and mosfet, right?
Thanks,
JG
I'm hoping these would keep the mosfets cool enough - they're rated at 56°C @ 4W.
Here's the link to mouser...
567-287-1ABE
I do believe I would need insulators between the heatsink and mosfet, right?
Thanks,
JG
the Salas Shunts draw constant current.
You can add a series Power resistor to each feed line and it will drop a fairly constant voltage.
10r and 200mA for CCS will drop 2V and dissipate 400mW
20r and 400mA drops 8V for 3.2W
An RC before the regs uses up spare voltage and cleans up the supply making for an easier job for the Shunt.
You can add a series Power resistor to each feed line and it will drop a fairly constant voltage.
10r and 200mA for CCS will drop 2V and dissipate 400mW
20r and 400mA drops 8V for 3.2W
An RC before the regs uses up spare voltage and cleans up the supply making for an easier job for the Shunt.
JG/Merlin,
You don't need insulators as long as the sinks are independent (ie not touching one another.)
Insulators would only make them less efficient at conducting heat away. Thermal paste is best.
Those sinks look borderline for a Hot Rod. They'll work, but with mosfets running hot, life expectancy will be reduced I think.
You don't need insulators as long as the sinks are independent (ie not touching one another.)
Insulators would only make them less efficient at conducting heat away. Thermal paste is best.
Those sinks look borderline for a Hot Rod. They'll work, but with mosfets running hot, life expectancy will be reduced I think.
What about a bleeder resistor after the caps? I have some 220K 5W Kiwame Carbon film on order for this purpose, as it was on the schematic I am following, but I am not sure of the effect they will have.
Not for 10R setting resistors. For low current setting with the two small resistors, yes. Insulators you will need only if the sinks are going to be touching the chassis or one another.
Project accomplished!
An externally hosted image should be here but it was not working when we last tested it.
To get the maximum
"switch and turn feeleing" i installed an Elma Switch for the input selector and the Blue Alps for the Optical Volume Control.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Here my new DCB1 besides my new AMP III and my Audionet multichannel pre-amp.
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An externally hosted image should be here but it was not working when we last tested it.
The design i made myself with a CNC program from Schaeffer AG in Berlin.
They also made the machining and lettering.
After the installing with the copper blocks, the sinks are ice cold
So the hotrod 0.6A installation follows. I must just order the 3R3´s.
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They have an excellent service and you have a few options how fast they build your order.
Oliver, my pre-amp is very similar to yours. DC-B1, relay selector and OVC. I've just been reading on the George/Uriah optical volume thread, where they both agree that the OVC should be in a temperature constant environment, or else it will not produce stable results. You might consider putting the unit inside a small aluminium hammond box or similar, within the case. I have just been reading about this here:
http://www.diyaudio.com/forums/anal...uator-new-passive-preamp-360.html#post2342781
Awesome build, by the way. You must be very happy with all your hard work! Very impressive.
http://www.diyaudio.com/forums/anal...uator-new-passive-preamp-360.html#post2342781
Awesome build, by the way. You must be very happy with all your hard work! Very impressive.
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if the sinks are cold then that is an indicator that the sinks are not dissipating any heat.After the installing with the copper blocks, the sinks are ice cold
It is not an indicator that the sinks are working well.
Hi Andrew,
before the installation and without the copper blocks, the sinks were a bit warm.
Now in the case, with the copper blocks between the sinks and the aluminum bottom, they are cold.
So the dissipation works very well, or where should i search the heat?
means the sinks were dissipating some heat.
means the sinks are not dissipating any heat.
No, the thermal resistance between the device and the heatsink is preventing the heatsink from getting warm.
How warm is the device?
If you say the device is cold, then ask yourself what heat is the device dissipating?