Hi Al,
The MJE340 has a lower collector current rating, but it should not matter here.
Double check the pin outs.
MJE243 might be better if you have, thinking of DC beta. Current rating is much higher (a waste) at 4A.
-Chris
The MJE340 has a lower collector current rating, but it should not matter here.
Double check the pin outs.
MJE243 might be better if you have, thinking of DC beta. Current rating is much higher (a waste) at 4A.
-Chris
Gaborbela, the gerber files can only be opened with special programs. Like Al said, it should be alright to just take the gerber files AND the excellon files and send them to the pcb house. Not all pcb houes can use eagle files.
Al, you're welcome to the party...
The mje340 should do the job, the pinout fits, and it just needs to be some standard bjt in a to126 case. A bd135-16 would also do the job. it's only the sensing device for the vbe multiplier, no high curents and no high voltage.
Chris, for c7 ceramic might be ok, it's highly biased (>60v) and sees only very small signal. At least c14 should not be ceramic... For higher freqs it gets nearly the full output voltage swing.
I also could send you some of the micas i used, they perfectly fit the board. (will take a few days)
Mike
Al, you're welcome to the party...
The mje340 should do the job, the pinout fits, and it just needs to be some standard bjt in a to126 case. A bd135-16 would also do the job. it's only the sensing device for the vbe multiplier, no high curents and no high voltage.
Chris, for c7 ceramic might be ok, it's highly biased (>60v) and sees only very small signal. At least c14 should not be ceramic... For higher freqs it gets nearly the full output voltage swing.
I also could send you some of the micas i used, they perfectly fit the board. (will take a few days)
Mike
anatech said:
How many do you need? I could mail you a couple, but the postage times to Canada might be longer than the delay from your distributor. 😉
Hi Mike, I thought that would be the case, but I was just a little worried as you mention troubles with stability with some component swaps. I could fix these issues over time, but it would be nice just to build an amp, (apart from GCs), that works first time at least once in my life! 🙂
I am sure that this one is that much tuned and proved that it would work first time, provided no mistake done during soldering etc. 😉
Yeah, it's not that I can't debug a circuit if I have to, it's just after various other projects I've been doing recently, it would be nice to have one work first time!
Al, typically symasym works at first powerup (after adjusting bias), you will get only problems if you are changing values or parts wildly. The vbe mutliplier is not directly in the signal chain, or does not apply any gain to the signal, so replacing it should not change stability.
With the 5.3 pcb you can decrease OL gain anytime by adding degeneration resistors to the input diff amp.
You have to be careful with the pinouts of the to92 transistors, the BC-types have reversed pinout compared to others, this is subject to double checking like polarity of elyts. If you use all original parts you can go simply by my photos on the symasym page. (Or the silk screen)
Even if it does oscillate, it does it at moderate levels of few mv's, not immediately burning up. (just sounding very bad)
What are you planning to use as input devices, mpsa18 or bc550c ?
Mike
With the 5.3 pcb you can decrease OL gain anytime by adding degeneration resistors to the input diff amp.
You have to be careful with the pinouts of the to92 transistors, the BC-types have reversed pinout compared to others, this is subject to double checking like polarity of elyts. If you use all original parts you can go simply by my photos on the symasym page. (Or the silk screen)
Even if it does oscillate, it does it at moderate levels of few mv's, not immediately burning up. (just sounding very bad)
What are you planning to use as input devices, mpsa18 or bc550c ?
Mike
Hi Mike
I will be using MPSA18s, I know I have a bag of 50 or so around here somewhere, I just can't put my hands on them right now!
I must admit, the temptation to fiddle may be getting the better of me and I might just tweak your Eagle files to allow the use of MJ15003/4 or MJ21193/4 in TO3... 😉
I will be using MPSA18s, I know I have a bag of 50 or so around here somewhere, I just can't put my hands on them right now!
I must admit, the temptation to fiddle may be getting the better of me and I might just tweak your Eagle files to allow the use of MJ15003/4 or MJ21193/4 in TO3... 😉
Hi Al, it should be easy to modify the pcb to use TO3s, just don't forget that the drivers also need to be mounted on the heatsink. (dissipating ~1.5w)
From the "slow transistor faction" i tried the MJL21196/5, they sound lovely, but miss the precision and clarity from the fast outputs like MJL0281/SC5200. I must admit that i did not match them... 🙄
And, the slower ones definitely need higher bias. (>100ma)
Another tip: Don't use the 1k pot for adjusting the bias, a 470ohm should be better.
Mike
From the "slow transistor faction" i tried the MJL21196/5, they sound lovely, but miss the precision and clarity from the fast outputs like MJL0281/SC5200. I must admit that i did not match them... 🙄
And, the slower ones definitely need higher bias. (>100ma)
Another tip: Don't use the 1k pot for adjusting the bias, a 470ohm should be better.
Mike
Yes, I appreciate they may not be ideal, but I have loads and loads of TO3 devices I really need to find a use for! Useful tip about setting the bias, thanks.
al/ still can't find the bag of MPSA18s...
al/ still can't find the bag of MPSA18s...
Hi Al,
I used 470R pots (thanks Mike) and expect it to fire up without too many troubles. I used all orginal numbers so far. I did use some heat shrink tubing around Q7 / 8. I will do the same with Q1 / 2 when I settle on the devices I want to use. You can see all the pairs are matched. Right now they are greased and pushed together.
Just run wires to some TO-3 sockets from the board as is. The drivers and bias can live in the original locations. If you match the outputs best you can I think you could reduce the bias. What I am seeing with these numbers are a 2:1 beta ratio, PNP to NPN. MJ15022/MJ15024 and MJ15023/MJ15025 I recall being closer.
Mike,
C14 and C7 are NPO ceramics right now. I have some GIANT 300 V micas also. The 300V were the smallest I could find so far. Let's see if I can locate some poly - whatevers with a 100V rating. The only polystyrenes I can find are 50 V.
I think I may try to redesign the PCB later for larger (more common) components. A larger PCB is okay given the heatsink size required. Rerouting will bring me back to the original grounding issues you had. At least I'll be able to find some in stock input coupling caps! 😉
-Chris
That's very kind, thank you. Mine should arrive some year. I am considering some Japanese numbers in the mean time. This poor board will be tinkered to death! 😉 So, no need for that.
I used 470R pots (thanks Mike) and expect it to fire up without too many troubles. I used all orginal numbers so far. I did use some heat shrink tubing around Q7 / 8. I will do the same with Q1 / 2 when I settle on the devices I want to use. You can see all the pairs are matched. Right now they are greased and pushed together.
Just run wires to some TO-3 sockets from the board as is. The drivers and bias can live in the original locations. If you match the outputs best you can I think you could reduce the bias. What I am seeing with these numbers are a 2:1 beta ratio, PNP to NPN. MJ15022/MJ15024 and MJ15023/MJ15025 I recall being closer.
Mike,
C14 and C7 are NPO ceramics right now. I have some GIANT 300 V micas also. The 300V were the smallest I could find so far. Let's see if I can locate some poly - whatevers with a 100V rating. The only polystyrenes I can find are 50 V.
I think I may try to redesign the PCB later for larger (more common) components. A larger PCB is okay given the heatsink size required. Rerouting will bring me back to the original grounding issues you had. At least I'll be able to find some in stock input coupling caps! 😉
-Chris
HI
Pinkmouse you dont have boards for these amp? I have boards for the Krell clone wich was design by you .
I sent the web site of Mike to http://www.pcbex.com unfortunatly no longer aswer to me . At first when I contact with he ask me to send the gerber file ,now I sent but no answer.
If some one knows in North America from were I can order pc board please let me know . Even from Europe is ok if I can pay with visa or pay pal and not to expensive .
Apex has the Toshiba power transistor for these amp.
Thanks
Regards
Pinkmouse you dont have boards for these amp? I have boards for the Krell clone wich was design by you .
I sent the web site of Mike to http://www.pcbex.com unfortunatly no longer aswer to me . At first when I contact with he ask me to send the gerber file ,now I sent but no answer.
If some one knows in North America from were I can order pc board please let me know . Even from Europe is ok if I can pay with visa or pay pal and not to expensive .
Apex has the Toshiba power transistor for these amp.
Thanks
Regards
Jeno, I wouldn't worry yet, it might take a few days for the pcb house to get around to looking at them, especially as it was just the weekend. I will be making my own boards for this amp, it doesn't seem worth a production run as they are single sided. So why haven't you built the Krell Clone yet? 🙂
Chris, you're probably right about just running wires from the board to the OPS, but I am an inveterate tinkerer so I may just redo the boards anyway to suit the components I have to hand...😉
Chris, you're probably right about just running wires from the board to the OPS, but I am an inveterate tinkerer so I may just redo the boards anyway to suit the components I have to hand...😉
HI
Pinkmouse I just receved the transformer from Plitron for the Krell clone. I waited for it 5 weeks , I have the boards from the last run. I will have to order the resistors and some another parts.
I will put it together soon , it just to much work with those large heatsinks.
May be when you do the boards for yoursel you can make two for me
I will pay for it 😀 ,
I did made pc boards before for the Hiraga amp and some anothers but the quallity is
.
I not even try these to do it , it would be very cheap.
Regards
Pinkmouse I just receved the transformer from Plitron for the Krell clone. I waited for it 5 weeks , I have the boards from the last run. I will have to order the resistors and some another parts.
I will put it together soon , it just to much work with those large heatsinks.
May be when you do the boards for yoursel you can make two for me
I will pay for it 😀 ,
I did made pc boards before for the Hiraga amp and some anothers but the quallity is
.I not even try these to do it , it would be very cheap.
Regards
Ryssen said:
What, like me, just over a year ago? 😉
Jeno, mine will be dead basic home made ones, you could make them just as easily yourself. Have a look at some of the PCB making threads here.
Hi Al,
If you are going to redesign the PCB, can we enlarge the component footprints? Might make layout easier and support thicker traces.
One problem I can think of right away is that you will have a fin spacing for a particular extrusion. Not a problem for a one-off but will make it difficult for anyone else to use the same layout without the same heatsink. The sockets tend to cover a lot of real estate.
You could use "flying PCB's" that only mount the outputs. Leads to the stock PCB. Wire the power and speaker output direct from the new boards. Just a thought. 😉
gaborbela,
Try Crimp Circuits in Toronto. They can do good work Crimp Circuits . They have been around a long time. Just got another folder from them at the EP&T show in Waterloo. Same guys are there too.
-Chris
If you are going to redesign the PCB, can we enlarge the component footprints? Might make layout easier and support thicker traces.
One problem I can think of right away is that you will have a fin spacing for a particular extrusion. Not a problem for a one-off but will make it difficult for anyone else to use the same layout without the same heatsink. The sockets tend to cover a lot of real estate.
You could use "flying PCB's" that only mount the outputs. Leads to the stock PCB. Wire the power and speaker output direct from the new boards. Just a thought. 😉
gaborbela,
Try Crimp Circuits in Toronto. They can do good work Crimp Circuits . They have been around a long time. Just got another folder from them at the EP&T show in Waterloo. Same guys are there too.
-Chris
Hi Al,
Well ..... You did say you may design a new board "because you like to tinker". 😀 I do too, but I don't like designing PC boards. I wish I could print a positive or transfer reliably. It would make my DIY life a ton easier!
Besides, I offered two easy ways out. You could have bailed easily. But no, not you! 😉
-Chris
Well ..... You did say you may design a new board "because you like to tinker". 😀 I do too, but I don't like designing PC boards. I wish I could print a positive or transfer reliably. It would make my DIY life a ton easier!
Besides, I offered two easy ways out. You could have bailed easily. But no, not you! 😉
-Chris
There is this company in Sweden http://www.electrokit.se/index.php
if you make 20 PCB 100x75mm you get them for 15.64 dollar each +shipping Wonder how many would be interested in a groupbuy?If you might be kind enoug to redo those gerbers,🙄 I cant
I could arange it,payment trhou paypal.e.t.c any interest?