Hi there,
having built +5 & -5 LT1028ACN & LM431 based SSR01 & SSR02. They all show a rock solid +/-4.98V, can't see lower on my DMM.
Now with a -15V.
Same, R12 being 499 in all SSR0x, but the DZ1 wich is a yellow Led. All starts fine with an -14.83V.
• this yellow Led is always on, isn't it supposed to go off after a while?
• what R to change in order to get -15V or better -14.98?
Regards,
Matthieu
The LED should be lit. This is a sign that you have a constant voltage across R4 and the regulator is regulating.
If you are using opamps it doesn't matter if you have 14.67, 14.83 or even 15.17 V as long it's stable. Around VR1 you have empty places for addition resistors. You can also tweak the gain a bit. Also there you have extra resistor locations. If you feel that this is important for you and you are not able to calculate yourself I can help you with this. For this I want to know used resistor values and also the reference voltage, measured directly over the LM431.
Hi Per-Anders,
yes I need as close as -14,98V
Right I have all R values like in your files for download but R12 to 499R, spare parts from my first SSR01 ;)
In the building instruction it's 470R, is this one of the trick?
If changing some R values, a // mix of R to make the right one is welcome.
I have -4.84V at the first pin of the LM431.
Side question, about the -5V one, I've found the LM337 to run warm without any load, maybe because of the same -25V as the -15 SSR02? Voltage drop story?
Even if my DMM shows a stable -4.98V... I've checked LM431 and it shows 0V at that first pin but -2.49V at the second one, same 2.4 as the +5 but the first pin! Maybe no problem here it's just me getting nervous at a fly passing by ;) The SSR01 at +5 is powered by +11V and stay barely warm.
Thanks,
Matthieu
Have you really used my BOM for -15V? The LM431 should have 7.50 V at the cathode. The gain should be 2 and you seems to have 3.
To see that everything is working OK. The LM431 should have 2.50 V +- 2% between ground (anode) and ref.
The regulator consumes some power so 5 V out and 25 V in will create some power losses and most of if is in the LM337. LT1028 is rather thirsty too.
Curious, but what is your need for 14.98V? (15V within 1.3‰)
Hi,
yes I've done it according to your BOM, but as I'm a bit "mindless" it's still possible that I've mixed parts or missed one
I have 4.84V between pin 2 & Grnd,
7.31 between pin 3 & Grnd,
0 at pin 1 & Grnd.
2.472V betwenn pins 2 & 3
The computer is away from the stuff so I can't keep in mind what pin is what in wich order :'(
The Reg is for a TDA1541A S1 wich perfom best with a nice -10V between its negative rails. I also like to "cut the hair in quarters" or "fuck the flies" (sorry french sayings to express someone very boring finding problems where there are none ;) ).
Thanks!
Matthieu
(defo a pretty kitty)
If you can tell me which resistor values you have I can calculate how to get near -15 V.
Hi,
you mean the real ones, not the BOM ones?
100% BOM ones but R12 a 499R.
I'll get the precise values this noon.
Edit:
here what I have on the board, close ones showing the same are in // I suppose,
R1 0.996K
R2 0.996K
R3 2.195K
R4 100R
R6 47.05R
R8 944R
R10 925R
R11 925R
R12 499R
R13 1.952K
R14 4.79K
R16 3.743K
R17 3.743K
Voilà !
A fast calculation shows that something is wrong here. Have you measured on soldered resistors?
Have you checked my BOM and compared?
Quote from: peranders on March 28, 2010, 03:13:57 PM
A fast calculation shows that something is wrong here. Have you measured on soldered resistors?
Yes, I know that's a bit stupid...
Quote
Have you checked my BOM and compared?
Yes, both pics (15 based but all R the same) & list
Can you tell me the values of the resistors, and of course the value which they are marked with?
I have a very good picture of the 15V, LM431 positive version which is exactly the same as the SSR02 when it comes to resistors.
http://sjostromaudio.com/hifi_pics/hifi_100pr/ssr01r0_15V_LM431.jpg
It's the exact copy of this picture but R12 and values are:
R1, R2, R8, R11 1k0
R3, R13 2k2
R4 100R
R6, R9 47R
R7 0R0
R10 39k
R12 499R
R14 10k
R16 5k6
R17 56k
R18, R19 nothing
J1, J2 Tin jumper
I've checked again, it's really like this.
Hope I can make that adjustment, telle me if more tests are needed.
Matthieu
Check my Excel file.
Ok that means I'll have to remove the R and check them.
I'll report my findings.
If you have 1% resistors you can consider them as "exact". Just change the ones who are different.
R15 is not on BOM nor picture, that may be where I'll get my way.
R15 is not used but I have it in my calculations (= GOhms).
10K 1% was 9.90, enough to drop what I needed ;)
Fixed!
Many thanks Per-Anders!
... and you have a calibrated multimeter?
My experience is that it's very rare to get resistors more than 0.3% wrong. Still if you want so exact output voltage you must also use a calibrated instrument.
Well I know my DMM, a good Chauvin & Arnoux, is out of tune. Maybe 15 years it has not been calibrated and it should be done.
You are right, to make good work use good tools, I'm on the ghetto mode...
Anyway I have a second pack of metal film resistors, but 1/8W only (it runs cold seems) and these 10K show between 10.01 and 9.98... all that 1/4W ones are around 0.992/0.996, all other resistors I have match the specs.
For me it's a bad batch :'(