jacco vermeulen said:
Here you go.
You beat me, K.I spent some time in the tax-free twilight zone in Switzerland.
Why Jacco? Did you have 50lbs of Hash for, "personal use"?
K-amps said:
You got it, i'm marketing a new kind of Swiss cheese.
This one you don't melt, but smoke it. I'm calling it Swashies.
I still don't get what Al is going to do with the exercise rack ?
It looks like a walking aid for disabled Krell owners.
jacco vermeulen said:
Be patient! Wait until the perspex gets fitted. 🙂
Upupa Epops said:
Yes, but square section copper is relatively expensive, whereas the plumbing pipe I'm using is pretty cheap, so if I decide I don't like this concept, (and being a designer, that's quite possible), when it's finished I can just chuck it away...
pinkmouse said:
NOW i get it!
It's an índustrial design 19'' amplifier rack for narcistic pcb layout developers with a PA background
(i'm already a patient)
For anyone interested in one of em hihi2000 cases mentioned a few pages ago.
I have two, and I decided to put one up for sale, probably next week or so.
I have two, and I decided to put one up for sale, probably next week or so.
Hmm, I'm feeling tempted!
Re: Case
Yes, but shipment would be very high. Something like $60 USD for economy shipment and $113 USD for priority shipment?
I should weigh the complete package first. Also I have not decided what to ask for the case.
rjkdivin said:
Yes, but shipment would be very high. Something like $60 USD for economy shipment and $113 USD for priority shipment?
I should weigh the complete package first. Also I have not decided what to ask for the case.
Re: PSU Configuration
Hi Robert, while the others banter among themselves, I'll try to answer your questions.
The bleeders can be very high, and could be like 10K 1/2 W, which would take a few minutes to dissipate the charge on your capacitors (say 40VDC) but that's not a problem. You just don't want the caps sitting around 1/2 charged for a long time, like hours, not minutes. No need to amputate them when a cut will do....hahah I make a joke! We all thought you were trying to build what's known as a "CRC" power supply which actually uses a 0.5 ohm resistor between (not across) the caps you were showing. Such CRC power supplies have less ripple and are a good thing (as Terry says), but not strictly necessary for the Krell.
rjkdivin said:
Hi Robert, while the others banter among themselves, I'll try to answer your questions.
The bleeders can be very high, and could be like 10K 1/2 W, which would take a few minutes to dissipate the charge on your capacitors (say 40VDC) but that's not a problem. You just don't want the caps sitting around 1/2 charged for a long time, like hours, not minutes. No need to amputate them when a cut will do....hahah I make a joke! We all thought you were trying to build what's known as a "CRC" power supply which actually uses a 0.5 ohm resistor between (not across) the caps you were showing. Such CRC power supplies have less ripple and are a good thing (as Terry says), but not strictly necessary for the Krell.
PSU Configuration
I've made a few corrections to my PSU design ....thanks for all the help! I'm considering either the single bleeder resistors R1 and R2 and adding a power LED circuit ahead of the rectifiers, or using higher resistance bleeders in series with an LED, but probably not both....any comments? (For now, both bleeder configurations are shown). Also, does it matter where the bleeders are located relative to the CRC? It doesn't seem like it should make any difference.
Also, Terry's idea to try the CRC series resistor both in the circuit and bypassed, sounds like a good idea, so I will probably try that.
Robert
I've made a few corrections to my PSU design ....thanks for all the help! I'm considering either the single bleeder resistors R1 and R2 and adding a power LED circuit ahead of the rectifiers, or using higher resistance bleeders in series with an LED, but probably not both....any comments? (For now, both bleeder configurations are shown). Also, does it matter where the bleeders are located relative to the CRC? It doesn't seem like it should make any difference.
Also, Terry's idea to try the CRC series resistor both in the circuit and bypassed, sounds like a good idea, so I will probably try that.
Robert
An externally hosted image should be here but it was not working when we last tested it.
Looks good, but-
1. no need burning up 3W in your bleeders, go with 10K or 20K and it will be just as effective.
2. If putting LEDs ahead of the rectifiers, note that LEDs don't like a significant reverse voltage (>5V) and may be destroyed by AC in excess of this. So either use another diode in series before them or use them with DC.
3. The more LEDs, the better, look at my link (below in my tag line). But that said, looks like you are using both LEDs and resistors to bleed, stick with resistors they will work better. I think a set of R's across the 1st or 2nd pair of caps would do it.
4. Those 0.5 R's are looking good!
1. no need burning up 3W in your bleeders, go with 10K or 20K and it will be just as effective.
2. If putting LEDs ahead of the rectifiers, note that LEDs don't like a significant reverse voltage (>5V) and may be destroyed by AC in excess of this. So either use another diode in series before them or use them with DC.
3. The more LEDs, the better, look at my link (below in my tag line). But that said, looks like you are using both LEDs and resistors to bleed, stick with resistors they will work better. I think a set of R's across the 1st or 2nd pair of caps would do it.
4. Those 0.5 R's are looking good!
lgreen said:
Thanks for the suggestions! Yes I was aware that you need a diode in series for half wave rectification for an LED on the AC side. Most power LEDs I have seen have also placed a small smoothing capacitior in parallel with the LED and resistor.
I've looked at your KSA many times. Its very impressive, but I can't find your bleeders in amongst all the hardware and wires. Are the LEDs on your front panel in series with your bleeders?
Robert
rjkdivin said:
.......lets just say your power supply will be more advanced than mine.........and since both rails will be evenly loaded by the same value of bleeders you won't have that annoying buzz when you turn it off!
Hi Rjk,
the LEDs are the wrong way round.
The pair of LEDs & dropper resistors would make good bleeders, you don't need any more.
Remember also the amps themselves will reduce the cap voltage to almost zero in a few seconds. The only time the bleeders will provide a benefit is when the amp is disconnected from the PSU, maybe for testing and then you need some protection from poking fingers and/or tools.
You still have all your good caps split either side of the 0r5 resistors. I repeat myself because I believe it is important that the final caps meet or get close to the amplifier's cap requirements.
The fuses ahead of the rectifiers and caps will see a big current at start up so you need T rated and big values, but then they provide little or no protection. Much better to put them after the caps then use F rated and lower values. Try about 50% of peak output current ( 8r needs F2.5A and 4r needs F5A).
the LEDs are the wrong way round.
The pair of LEDs & dropper resistors would make good bleeders, you don't need any more.
Remember also the amps themselves will reduce the cap voltage to almost zero in a few seconds. The only time the bleeders will provide a benefit is when the amp is disconnected from the PSU, maybe for testing and then you need some protection from poking fingers and/or tools.
You still have all your good caps split either side of the 0r5 resistors. I repeat myself because I believe it is important that the final caps meet or get close to the amplifier's cap requirements.
The fuses ahead of the rectifiers and caps will see a big current at start up so you need T rated and big values, but then they provide little or no protection. Much better to put them after the caps then use F rated and lower values. Try about 50% of peak output current ( 8r needs F2.5A and 4r needs F5A).
I have some Rifacaps (1000uF, 100V) and some kind of militarygrade caps (1uF). Is there any advantage och adding one of each in parallell and use them just infront och the outputstage?
Hi,
the electros would be ideal for on board decoupling if you can make them fit the space and pitch provided.
The 1uF could be a help for bypassing, are they film or ceramic?
the electros would be ideal for on board decoupling if you can make them fit the space and pitch provided.
The 1uF could be a help for bypassing, are they film or ceramic?
They shuld be film.
They are made by Sprague to be used in Aviation. They where used in the guidingsystem of an older model Fighterjet.
The same friend who gave them to me said that if I where to Saw one in half I would see something that looked like goldfilm (among other things).
They are made by Sprague to be used in Aviation. They where used in the guidingsystem of an older model Fighterjet.
The same friend who gave them to me said that if I where to Saw one in half I would see something that looked like goldfilm (among other things).