You mean the transformer's power rating I would suppose. If you set 500mA CCS that would mean 14VA power at 28V AC secondary and to stay cool it should be rated at 30VA the least.
I want to test my BiB tonight but I realized that I only have the 20 Ohm resistor home that was in the fantastic kit from Teabag but it is only 5 watts. I will run 7.6 volt with a max current of 1 A so I should need a 7.6 Ohm minimum with 10 watts. I happen to have 6.8 Ohm 25 watt laying around but is it wise or should I wait till tomorrow when I can get 20 Ohm 10 watts?
How come and you will have 7.6V across R101? Maybe 7.6V is your CCS LEDs total added Vf? You should subtract the over 4V Q101's Vgs from that voltage if so (find what Vgs the Mosfet's datasheet shows at 1A Idrain). The CCS setting will be be governed by VR101/R101 result. That resistor's Wattage spec will also drop a lot in that case.
On the other hand if you are talking the test load resistor then 20 Ohm 5W will endure for a while although hot as it will draw 0.38A at 7.6V output and that makes 2.88W. Don't rest it on any other surface than metal, or just let it hang on air. You should not draw all the available current else this reg will go into current limiting mode and its Vout will drop exactly like the bench PSUs do when set in CC protection mode.
I'm sorry....
Salas, I am sorry for my very undeveloped and not so clear question yesterday (blame the late hour).
I was referring my question to Vout which means the dummy load resistor and since I was not clear enough to describe my thought maybe it was good not to try the SSLV1.1 yesterday anyway.
Don't mess with electronical stuff when not absolutely clear in mind (alcohol, drugs, waaay toooo much coffee (or too little for some) or too little sleep doesn't improve the brain activity, at least not when coming to engineering stuff. I know people who are more artistic and they don't mind doing them all when working but as I said, not recommendable)
I am going to test run the BiB today (now it is morning so I will get my bigger dummy load resistor (11 W) anyway cause I will need it for another project as well) and since I will have 7.6 V out running 1A at a maximum the test load have to correspond to that value, 7.6W and that is what I did not have at home yesterday.
Thank you anyway for your "in the middle of the night"-answer. Salas I really have to say thanks both to you and Teabag working around this design and the GB distribution and I wonder, as many have already pointed out, when do you sleep?
I did the Reflector D earlier this week and it is spot on my needed 3.6 V, 500 mA for the digital line on my Playstation 1 CD player so now when the drive get new 7.6 volt, 1 A PSU I am really curious to put it together and listen again.
Salas, I am sorry for my very undeveloped and not so clear question yesterday (blame the late hour).
I was referring my question to Vout which means the dummy load resistor and since I was not clear enough to describe my thought maybe it was good not to try the SSLV1.1 yesterday anyway.
Don't mess with electronical stuff when not absolutely clear in mind (alcohol, drugs, waaay toooo much coffee (or too little for some) or too little sleep doesn't improve the brain activity, at least not when coming to engineering stuff. I know people who are more artistic and they don't mind doing them all when working but as I said, not recommendable)
I am going to test run the BiB today (now it is morning so I will get my bigger dummy load resistor (11 W) anyway cause I will need it for another project as well) and since I will have 7.6 V out running 1A at a maximum the test load have to correspond to that value, 7.6W and that is what I did not have at home yesterday.
Thank you anyway for your "in the middle of the night"-answer. Salas I really have to say thanks both to you and Teabag working around this design and the GB distribution and I wonder, as many have already pointed out, when do you sleep?
I did the Reflector D earlier this week and it is spot on my needed 3.6 V, 500 mA for the digital line on my Playstation 1 CD player so now when the drive get new 7.6 volt, 1 A PSU I am really curious to put it together and listen again.
Test
Did have time late in the evening to do the test that I wanted..... happy!
Have a last question though, should I have bigger heat sink??
I started up the SSLV and adjusted the voltage on the trimmer til I got 7.6 volts as I wanted and after 4-5 minutes I did some adjustment since it was slowly crawling upwards (within 10 mV). After yet another 20 minutes I had to take it back some 12-14 mV but after that it was fairly stable, flickering between 7.599 and 7.600 volts.
Checked some temperatures with a probe and had directly on Q301 (the joint between plastic and metal), 52 degrees Centigrade and on Q306 just above 41 degrees Centigrade. Seem to be ok temperatures but if I understand the circute correct, now when I have tested with a dummy load then I use the full capacity of the SSLV (this is a question)?
The SSLV is set up for 1 A but most of the time, during playing CD:s it will only use about 450 mA so what I wonder is, will I have higher temperature due to more dissipation or will I be ok as it is?
Did have time late in the evening to do the test that I wanted..... happy!
Have a last question though, should I have bigger heat sink??
I started up the SSLV and adjusted the voltage on the trimmer til I got 7.6 volts as I wanted and after 4-5 minutes I did some adjustment since it was slowly crawling upwards (within 10 mV). After yet another 20 minutes I had to take it back some 12-14 mV but after that it was fairly stable, flickering between 7.599 and 7.600 volts.
Checked some temperatures with a probe and had directly on Q301 (the joint between plastic and metal), 52 degrees Centigrade and on Q306 just above 41 degrees Centigrade. Seem to be ok temperatures but if I understand the circute correct, now when I have tested with a dummy load then I use the full capacity of the SSLV (this is a question)?
The SSLV is set up for 1 A but most of the time, during playing CD:s it will only use about 450 mA so what I wonder is, will I have higher temperature due to more dissipation or will I be ok as it is?
Your thermal drift looks normal for this circuit. Its a hot shunt reg with a minimalistic passive voltage reference. So things need some time to get warm and settle.
The CCS MOSFET's dissipation will remain as is while the output MOSFET's dissipation will be different depending on load's consumption. The less current it goes to the load the more spare remains to be burned on sink. Dissipation Q301 = VinDC-VoutDC * CCS set current. Spare current = CCS set current - load's average demand. Dissipation Q306 = VoutDC * spare current.
The CCS MOSFET's dissipation will remain as is while the output MOSFET's dissipation will be different depending on load's consumption. The less current it goes to the load the more spare remains to be burned on sink. Dissipation Q301 = VinDC-VoutDC * CCS set current. Spare current = CCS set current - load's average demand. Dissipation Q306 = VoutDC * spare current.
Do you use C101 Vref filter electrolytic for best noise? If yes its normal to wait longer than with film cap as its high capacitance charges up by current it steals from the Vref which is limited and climbs bit slowly especially towards the end, which also works for safety like having a slow start feature to never overshoot voltage spikes during power on.