at least you have a part-list to make it a little bit easier 🙂
only thing you should pay attention ir 560r in series with relay - it depends on relay coil resistance and it is not "must be" 560r - it should have enough resistance (and power) to get relay voltage to it´s coil and 560r is a solid starting point for 12V relay´s.
good luck with SR150 DIY! 🙂
44250,thanks for telling me.i can understand what you suggest me.i like your true spirit. may god make you happy.
hi apex sir, is c5200 and a1943 good transistor?there is c5200 printed on your sr 800 and on h900 also.it show that you used that transistor in your amp.i also use this pair in h900 but after one hour they are start to down now i will replace it with on semi device.in my town local pa amp manufacture also using c5200 for 1500w channel.what is truth about these transistor?what is your thinking.please share with love.this is very important for all diy so please reply.
SR250H,in progress:
(there will be lateral SR250, and smaller versions irfp / 2sk-sj with one pair of bipolar transistors in output-4 versions in total)
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the point would be to play a bit in order to get first watt or two in a-class,make mosfet to play to about 30-35W / 8r and than to get all the help needed from output BJT pair. i believe that i will build smaler lateral version because it will give me enough power and i have output transistors. before i do any pcb´s i must check out if it is matching schematics,and to adjust resistors in bias circuite. for lateral mosfets there should be a little less Ugs and bias transistor probably will not be needed but practise will tell.
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backside
Cable jumper on the backside sir...
How mA for the bias i suppose ti give sir?
Cable jumper on the backside sir...
How mA for the bias i suppose ti give sir?
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Regard 44250, fast progress!!!
For V_be biasing circuit with laterals in output we`ll need only R16 - 150R and P1 - 500R multiturn (10 turns) trimmer pot.
Because for laterals output pair in hybrid version with their positive temp drift we will eliminate:
-T14 V_be bipolar
-R15 put 0R or short
with 10-11mA biasing current (VAS CCS) we`ll have
-min U_bias 1,5V (150R)
-max U_bias cca 7V (150R + 500R trim.pot)
and we needs cca ( 2x 1,1V (for Ugs treshold typ laterals) + 2x U_be (for U_be drivers) + 2x deltaU_R (for R13, R14)) = TOT typ 3,7 - 3,9V
-start biasing with P1 at 0R and gradually turning trimmer with DMM on mVDC range over R8 (or R7 - 0R39) and find 55mV - 60mVDC reading,
this is minimum bias current for output mosfets pair - 150mA.
Both bipolars output pairs are in STDBY mode, they need about 0,7-0,75V treshold voltage over R7-R8 for starts conducting.
With bias current cca 250mA we have:
-classA region with "mosfet solo" - cca 2Wrms/8R0
-classAB with "mosfet solo" - cca 16-18Wrms/8R0 with R7, R8 - 0R39, and with 0R33 we get almost 25-30Wrms/8R0
If you have large heatsink, tray biasing with more current, you will have more power in classA push-pull region and also minor THD.
Don`t exaggerate, the THD improves only slightly, on 3-4th decimals range 🙂
The drivers MJE340/350 are biased also in classA @15mA (R6 = 560R) or with cca 25mA (R6 = 470R)
and in my opinion is enough current "storage" for driving mosfets gate charge + R_gs 2K2 without leaving classA.
R6 must be at least 1/2W for 560R or 1W for 470R.
-classAB hybrid 150Wrms/8R0 and klipping occurre/appears at 175-180Wrms/8R0 with PS +/-55VDC and +/-70VDC for input+VAS section.
Dragan
PCB??
thanks
regard
Does someone build this project??? where is post/threads, i want to try this.
thanks
regard
You're welcome, Mile.
I'm not in position to build anything, so I spend my free time drawing pcbs.
I'm not in position to build anything, so I spend my free time drawing pcbs.
Hi dobrivoje, beautiful work!
Can you draw a pcb for this Apex buffer? Many Apex amplifiers can be used with this.
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