JSR04, CeeVee wonders

[CeeVee]

heaveno Per-Anders,

This is precisely my first question to you....got my board from you yesterday, and as i want this for my ORION ASP i need +- 12 V.

Actually the value for R45 in this case is closer to 4k87 ohms..RS components part number 506-5226

my question is about P1, what voltage is supposed to be at R33 R37 mid point ? ie: eliminating R35 and P1 what value should i have for R33 ?

Carlos AKA CeeVee

[peranders]

Under normal conditions it's not necessary to have exactly +- 12 volt. The main thing is that the voltages are fairly equal.
The voltage at R33-R37 is exactly the same as the reference voltage.

If you want 12 volts out, see the first post here!

Adjust the LM431 to 6 volts and let the gain be 2 which means R33 and R39 = 1k, don't use R37, R35, P1.

[CeeVee]

'Lo again Per-Anders,

Seems like i can't edit my own posts ..."heaveno " means "heaveno " in thick finger land....hehe.

Anyway, thanks for your practical apraisal...i'm going to send for the components and bug you later if i make a mess of things....if not i'll send you some pictures ( ...under 2M, i know ) of the progress.

One thing is for sure, i'm going to follow this forum closely ...i see Mauro is here as well, his amps are on my list !

[CeeVee]

...Ok....I'll say Hi

Your forum will NOT let me write this most common of english greetings....????

[peranders]

I have just tested to create an user and edit afterwards. It works. Did you click at "modify"? I split this thread, maybey you can't edit the first post? Anyway, normally you'l be able to edit your post anytime.

[CeeVee]

Hi Again Per-Anders,

Got the Board...looks as good as i expected, got components from Digi-Key and RS Components.
Got working...hehe

Anyway, i have some questions, some quite basic but i want to do it right, here goes:

I'm doing it as +-12 v, i want 1A output or more but not necessary.

1 - Got Panasonic LC series 100 microF , Nipon Chemi Con KMH series 4700 MicroF main caps...are these OK ?

2 - Input rectifier, do need to put 1N5407 in parallel with 1N 4007 or are you indicating an option ?

3 - I notice that you do not include the POS POST PRE-Regulator in your board ( Picture on site ), why is that, should  i do this as well ?

4 - You have a zero ohm link in place of the 100 ohm resistor R49....why ? which sould i put in ?

5 - You do not include C37, I also use the AD825AR, should i ?


Excuse all the questions but i don't want to ask even more later....hehe

NOTE:I Got the components from Digikey because if we order from the european interface we do not pay import duties...very usefull and mailing cost is cheaper for me than ELFA....components are also much cheaper and delivery is FAST.

:-) Thanks

[peranders]

Note that you must design for max current, not a limit and more so 1 A or more must be max something. This has to so with chosen parts like transistors, diodes, cooling, current limiting resistors etc.

1 Probably OK

2 One diode, there is an option for different sizes of diodes.

3 What? Can you explain what you mean?

4 R49 = 0 ohms

5 C37 not used

[CeeVee]

Your schematic shows D9-R17-C25... as POS-POST-Pre-Regulator.

In Your picture you do not use these....can you explain please.

[peranders]

This is an option. Normally you will take supply voltage for the opamps from the output voltage. If you output voltage is very low, say less than 5 volts and the opamp won't work with less than 5 volts it gives you the possibility to use more types of opamps. R19, C27 should be used.

[CeeVee]

Ahhh ok in my case not needed, as for the rest

... i want to set max current to 1A but transitors have capacity for more: i use D44H11 ...and D45H11.

input diodes i plan to use 1N5407.

output current  limit resistor has been set to 0,68...1A.

what i mean by: "....or more", is that in future if i need a bit more current all i need to do is change the current limiting resistors ( R27//R29=0,68 ohms  and R11=5,6 ohm, exclude R9).
The transformer is +- 18V 50 VA.

is this ok ?

[peranders]

Correct but 0.68 ohms may be a bit tight if you really want to take out 1 A. Remember that the Vbe is 0.65V at room temperature and will decrease with 2 mV/Deg.