I'll be back here Tuesday to let all know the outcome of the shipping project!! Then its off to Rock Springs.....
Mark
Mark
Mouser: $700.00
Welbornelabs: $280.00
Digi-key: $290.00
sub-sub Total: $25.40
Packing: $1.00
PayPal: 3% =.80
Total: $27.20
Shipping: $6 in country, $12.00 out
This looks like the numbers for 50 channels...
Taking orders @ stgrab@yahoo.com for this week. Will order on Friday.
Welbornelabs: $280.00
Digi-key: $290.00
sub-sub Total: $25.40
Packing: $1.00
PayPal: 3% =.80
Total: $27.20
Shipping: $6 in country, $12.00 out
This looks like the numbers for 50 channels...
Taking orders @ stgrab@yahoo.com for this week. Will order on Friday.
Hi guys,
I've got a couple of questions.
The wife and kids are off to a training camp this weekend so I will have a lot of time on my hands. From what Mark is saying, I should have my boards by then so I would like to start building them. I was trying to hold out for the GB on parts but that doesn't look like it will work out for me. So here are my questions.
Earlier, a few folks said that 1/4w resistors will work fine for most all of the spots except for the ones in series with the zeners and of course where 2w or more are called out for. So I'm asking:
1) What advantage is there to using 1/2w resistors over 1/4w when 1/4w is sufficient?
2) If I decide to go with 1/4w, which resistors are the ones that "need" to be 1/2w?
3) With a choice of these pairs of outputs, which would be the best to use for this amp?
MJL4281/4203
MJL3281/1302
MJL21193/21194
Any advantages to one pair over the other?
4) Earlier jacco recommended using base resistors. I don't think I used those on my first build. What is the advantage/disadvantage of those and if I should use them would I just use the value called out in the BOM?
5) I bought two of these. I plan on going mono-block with this amp. Do these look adequate and how much filter cap should I use?
Thanks so much, Terry
I've got a couple of questions.
The wife and kids are off to a training camp this weekend so I will have a lot of time on my hands. From what Mark is saying, I should have my boards by then so I would like to start building them. I was trying to hold out for the GB on parts but that doesn't look like it will work out for me. So here are my questions.
Earlier, a few folks said that 1/4w resistors will work fine for most all of the spots except for the ones in series with the zeners and of course where 2w or more are called out for. So I'm asking:
1) What advantage is there to using 1/2w resistors over 1/4w when 1/4w is sufficient?
2) If I decide to go with 1/4w, which resistors are the ones that "need" to be 1/2w?
3) With a choice of these pairs of outputs, which would be the best to use for this amp?
MJL4281/4203
MJL3281/1302
MJL21193/21194
Any advantages to one pair over the other?
4) Earlier jacco recommended using base resistors. I don't think I used those on my first build. What is the advantage/disadvantage of those and if I should use them would I just use the value called out in the BOM?
5) I bought two of these. I plan on going mono-block with this amp. Do these look adequate and how much filter cap should I use?
Thanks so much, Terry
Shipping is a one time item applied AFTER the cost channels are summed.
Now this is within reason... If you order 30 channels please expect your shipping to be slightly higher.
Also please note that these prices were not "padded" or inflated in any way. The cost was plainly stated here on the thread and other members got the price quotes for this price.
This is being done at cost, and all money spent will be on the "quality" of the components.
Now this is within reason... If you order 30 channels please expect your shipping to be slightly higher.
Also please note that these prices were not "padded" or inflated in any way. The cost was plainly stated here on the thread and other members got the price quotes for this price.
This is being done at cost, and all money spent will be on the "quality" of the components.
Hi Still4given,
look up the spreadsheet I posted for the Leach zener. Substitute the KSA values and you'll find that you do not need 2W resistors.
There is no advantage in using 500mW or 600mW resistors over 250mW when each are running at tens of mW. I would expect there to be a slight advantage with the higher dissipation version when power exceeds about 125mW due to lower resistance change due to temp rise. I do not know if this would be audible. I posted a note about resistor powers to be dissipated way back, I presume you copied it into a KSA file!
With all the research you have been doing, you will be an expert in calculating resistor dissipation power by now. So you can correct my original post if it contained any errors.
look up the spreadsheet I posted for the Leach zener. Substitute the KSA values and you'll find that you do not need 2W resistors.
There is no advantage in using 500mW or 600mW resistors over 250mW when each are running at tens of mW. I would expect there to be a slight advantage with the higher dissipation version when power exceeds about 125mW due to lower resistance change due to temp rise. I do not know if this would be audible. I posted a note about resistor powers to be dissipated way back, I presume you copied it into a KSA file!
With all the research you have been doing, you will be an expert in calculating resistor dissipation power by now. So you can correct my original post if it contained any errors.
Hi Still4given,
those 500VA transformers seem to be quite nice but there is something wrong with his test figures.
4A input at 120Vac = either 480VA or 960VA
545 W output does not compute for either input????
the regulation seems OK upto 303w output. He is quoting about 4.3% but by 545watts the regulation has jumped to 10% instead of 8.7%. Again this seems odd, experimental error maybe.
500VA should have a regulation of about 5% or 6% at max output into a resistive load.
those 500VA transformers seem to be quite nice but there is something wrong with his test figures.
4A input at 120Vac = either 480VA or 960VA
545 W output does not compute for either input????
the regulation seems OK upto 303w output. He is quoting about 4.3% but by 545watts the regulation has jumped to 10% instead of 8.7%. Again this seems odd, experimental error maybe.
500VA should have a regulation of about 5% or 6% at max output into a resistive load.
rabstg said:
Troy - it looks like the Mouser total doesn't include the 5k pot needed for R105 and R126 (per Jan's BOM)
Mouser Part #: 652-3266P-1-502
100 in the checkout cart comes up to $226.00
when adding the additional pots (and updating paypal fees) my calcs show the total @ $31.85
~Brad
Hi Andrew,
I wish I was an expert by now but saddly no.
I am learning all along but mostly from my mistakes.
I believe the 2W resistors are for the emitters of the drivers. They are carring a bit of current I believe. The rest I will use 1/4W.
Thanks
I'm having trouble finding silpads for the TO-264 transistors. Do any of you guys know a source?
Thanks. Terry
I wish I was an expert by now but saddly no.
I am learning all along but mostly from my mistakes.
I believe the 2W resistors are for the emitters of the drivers. They are carring a bit of current I believe. The rest I will use 1/4W.
Thanks
I'm having trouble finding silpads for the TO-264 transistors. Do any of you guys know a source?
Thanks. Terry
still4given said:Hi Andrew,
I wish I was an expert by now but saddly no.
I am learning all along but mostly from my mistakes.
I believe the 2W resistors are for the emitters of the drivers. They are carring a bit of current I believe. The rest I will use 1/4W.
Thanks
I'm having trouble finding silpads for the TO-264 transistors. Do any of you guys know a source?
Thanks. Terry
Both Parts Express and MCM have them.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=055-395
Mouser and Digi-Key also.
kmj said:
I suppose that would be so if everyone was using the TO-264 outputs. Some are using the TO-3s I think.
Blessings, Terry
kmj said:
It is TO-247 or TO-3P. They are the plastic package.
TO-3 is the "old fashion" metal can.
There are no output transitors in these kits due to some using metal and some using plastic.
googler said:
Doah!... Price change. It is now $31.85 x N + shipping.
Paypal address is stgrab@yahoo.com. Email me for address if your sending a money order.
For the late comers to the thread, these parts should also work with Jan's boards.
GB close out is Friday. I will order over the weekend.
I will get shipping materials this week and start labeling.
I bought a new fan today and it is a bit louder than the other one was but mostly wind noise. It is pushing more air. I found if I hooked a couple of 150ohm 5W resistors in series with the fan it is very acceptable. Are 5w resistors OK to put in series in a 120v line to drive a fan that draws 0.1 amps? Can I go lower wattage on the resistors?
Thanks, Terry
Thanks, Terry
resistors
In case you are asking whether resistors are rated for certain voltages like capacitors, they are not, you only need to worry about the power that is dissipated in the resistor being higher than the power for which it is rated for.
So, measure the AC voltage across each resistor, then use P=V*V/150. If P is less than 5 then you are A-OK.
Is your "new" krell going to be a KSA 50 or KSA 100?
In case you are asking whether resistors are rated for certain voltages like capacitors, they are not, you only need to worry about the power that is dissipated in the resistor being higher than the power for which it is rated for.
So, measure the AC voltage across each resistor, then use P=V*V/150. If P is less than 5 then you are A-OK.
Is your "new" krell going to be a KSA 50 or KSA 100?
Re: resistors
Not exactly true.
120 volts and 0.1 amps means the fan has a resistance of 1200 Ohms.
With two 150 Ohms resistors added in series total resistance becomes 1500 Ohms.
Means the current through the fan coil becomes 12/15*0.1=0.08 amps.
The power dissipated in each resistor is 0.08*0.08*150= 0.96 watt.
As the voltage is AC, this is an average value, peak value is twice as high, around 2 watts.
lgreen said:
Not exactly true.
120 volts and 0.1 amps means the fan has a resistance of 1200 Ohms.
With two 150 Ohms resistors added in series total resistance becomes 1500 Ohms.
Means the current through the fan coil becomes 12/15*0.1=0.08 amps.
The power dissipated in each resistor is 0.08*0.08*150= 0.96 watt.
As the voltage is AC, this is an average value, peak value is twice as high, around 2 watts.
Hi Jacco.
No!
The motor will draw almost the same current but, due to turning more slowly, will develop less back emf . The drop in voltage across the resistors will match the reduction in back emf.
So it would be close enough to assume the same current through the resistors to calculate the volts drop and then prorata the speed to the new motor voltage.
The flow rate will probably drop by the square of the motor speed, Can anyone confirm?
No!
The motor will draw almost the same current but, due to turning more slowly, will develop less back emf . The drop in voltage across the resistors will match the reduction in back emf.
So it would be close enough to assume the same current through the resistors to calculate the volts drop and then prorata the speed to the new motor voltage.
The flow rate will probably drop by the square of the motor speed, Can anyone confirm?
Fan laws state that flow is directly proportional to speed, while the pressure available is proportional to the square of speed. Power is proporitonal to the cube of speed. One reference: http://www.efisystemsgroup.com/fanlaws.htm
In our applications we are not likely to need to worry about the pressure loss with slowing the fan.
In our applications we are not likely to need to worry about the pressure loss with slowing the fan.