4 pairs of MKT1822 / MKP1837
Got the boards today Sir Rudi plus the resistors, but I think you forgot to include the 4 pairs of MKT1822 / MKP1837 which I ordered together with the boards.
best regards,
Marjohn
You will have them, Marjohn.
Many thanks for your PAYPAL transfer.
Best regards - Rudi_Ratlos
Got the boards today Sir Rudi plus the resistors, but I think you forgot to include the 4 pairs of MKT1822 / MKP1837 which I ordered together with the boards.
best regards,
Marjohn
Marjohn, you are absolutely right! I forgot to put your capacitor order into my EXCEL sheet.
I apologize very much.
I will send you an EMail.
Best regards - Rudi_Ratlos
No problem at all Sir, you can include the capacitors on my order in the other group buy.
many thanks,
Marjohn
Carl, please check the polarity of C4 / 470µF / 16V.
I will have a closer look at it later on.
The MICA capacitors that your ordered, are very good!
I ordered the wrong ones, ,with a much too wide grid and too thick legs, and I spoiled the nail-file of my spouse. O dear!
Best regards - Rudi_Ratlos
Carl: you do not have to do a new DIGIKEY-order for the 22K resistors!
They are just to delimit the current flowing through the LEDs!
Take a 10K, 6K8, 4K7, ..., use Ohm's law: 35V rail-voltage - 2V forward drop across the LED - divided by some mA - giving the value of the resistor.
I will have a closer look at it later on.
The MICA capacitors that your ordered, are very good!
I ordered the wrong ones, ,with a much too wide grid and too thick legs, and I spoiled the nail-file of my spouse. O dear!
Best regards - Rudi_Ratlos
Carl: you do not have to do a new DIGIKEY-order for the 22K resistors!
They are just to delimit the current flowing through the LEDs!
Take a 10K, 6K8, 4K7, ..., use Ohm's law: 35V rail-voltage - 2V forward drop across the LED - divided by some mA - giving the value of the resistor.
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Ryan,
a transformer with 2 x 28VAC secondaries will give you about +/- 39VDC (roughly) after rectification.
Please take in account deviations in mains voltage, ..., as well.
This voltage may be critical for "sensitve" input transistors, like the 2SK170.
I therefore recommend you to solder the cap-multiplier and use a Z036 Zener-diode so that the frontend's voltage will be delimited to 35.3V (roughly).
Best regards - Rudi
Rudi,
Do I understand you correctly: I only need to replace the 33V zener with a 36V zener in the cap multiplier for safe operation at 39V rails?
Thanks,
Ryan
Ryan, I advise you to buy 2 pairs of 36V and 39V - Zener Diodes and measure them before use.
Zener diodes usually have an allowance (tolerance) of 10%!
If you want to use your 2 x 28VAC transformer and want your input transistors (f.e. 2SK170) being protected from damage
due to over-voltage (Vgds = 40V !), then use a 39V Zener (resp. 36V).
This will delimit the frontend-voltages to 38.4V (35.4V respectively).
The one, who has the best knowledge, how to operate a SYMASYM from higher voltages than 25VAC, is EVETTE.
As far as I remember, EVETTE operates one of his SYMASYMs from +/-50 VDC.
Joseph: is there anything you changed (exept rail-capacitors) to operate the SYMASYM from such high voltages?
Which type of input transistors did you use?
Best regards - Rudi_Ratlos
Zener diodes usually have an allowance (tolerance) of 10%!
If you want to use your 2 x 28VAC transformer and want your input transistors (f.e. 2SK170) being protected from damage
due to over-voltage (Vgds = 40V !), then use a 39V Zener (resp. 36V).
This will delimit the frontend-voltages to 38.4V (35.4V respectively).
The one, who has the best knowledge, how to operate a SYMASYM from higher voltages than 25VAC, is EVETTE.
As far as I remember, EVETTE operates one of his SYMASYMs from +/-50 VDC.
Joseph: is there anything you changed (exept rail-capacitors) to operate the SYMASYM from such high voltages?
Which type of input transistors did you use?
Best regards - Rudi_Ratlos
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