JSR03 - information

[Keljian]

just a small update, I'm planning on a case similar to this one :

http://www.briangt.com/gallery/nigc-srmcgee

building it from scratch using carbon fiber, blackwood, aluminum and a few other things.. should come out really nice when it's done

[Sigurd Ruschkowski]

Looks good on the photos.

Carbon fibre is really looking great! I am using it on my modell cars and boats.  My next preamp will also be in hardwood of some kind. Probably with an inner box of Al or copper plate/foil for shielding.
As a matter of fact, carbon fibre is conductive :-)


Sigurd

just a small update, I'm planning on a case similar to this one :

http://www.briangt.com/gallery/nigc-srmcgee

building it from scratch using carbon fiber, blackwood, aluminum and a few other things.. should come out really nice when it's done

[Keljian]

well there have been a few setbacks, one that I need some browndog adapters for the amplifier, and two that I forgot to order some caps. The JSR03 board came(thanks PA), as did the bulk of the parts, but some are still due. it looks like this will be going by the end of next week as opposed to this week.

[Keljian]

well, the JSR03 is being a real pain, the prop caps don't  fit - so there's much lead bending (I'm going to have to use polyester for a few) all the other components are really cramped, and the RN60D resistors are just too big (trying to tombstone and solder them on both sides of the board, but struggling. here I am wishing I had bought the SMD version and parts for it.

I'll persist and see if I can get it working

[peranders]

I think you are working backwards a bit. Check first what the part should look like, then deside what to buy. The design goal was to make a small board for "normal" parts, at least at normal size.

You can use the solder side also if you spacers high enough.

[Keljian]

(note I haven't cleaned the flux yet, hence the messyness


it's working, however the output voltage is wrong - 17.95v (stable) (I'm feeding it 29v for test purposes)

I need above 28v.

R7 = 510R
R8=  2.15k
R9= 680R

(mistake in typing, not in the circuit)


parts substitution:

T4 = d44h11 output transistor
T2,T5= BC557
IC2 = LM329
IC4= AD797

Note one of the pads lifted during desoldering hence the abnormal lead bending of c13

help please?

[peranders]

Looks good but you should use D44H11 OR BD139, not both! This is an option for TO126 or TO220 transistors. The same thing applies for the other transistors, TO92 or SOT23 types.

Notice also C9, should not be mounted.

I adwise you read the circuit description so you will see what you should mount and what you should omit. There are some options in the design which you must be aware of.

If you won't use the SENSE function you must put some tin on J1 and J2.

R9 and R8 isn't right. The gain forumla is Vout = Vref*((R8/R9)+1)

I see that you have chosen AD797. I have not yet tested it with this opamp but from what I know the regulator gets a bit more sensitive against capacitive load. AD825 is much better in this sense. Still if you have at least 50 mm wire to the load it will probably work alright.

One way to check if the regulator work properly is to measure the voltage  at the inputs of the opamp. They should have EXACTLY the same voltage. One other way to find out is to load the regulator. The voltage drop should be less then 1 mV at the lowest connection and some more at the board edge where you have some millivolts.

[Keljian]

Looks good but you should use D44H11 OR BD139, not both! This is an option for TO126 or TO220 transistors. The same thing applies for the other transistors, TO92 or SOT23 types.

Notice also C9, should not be mounted.

I adwise you read the circuit description so you will see what you should mount and what you should omit. There are some options in the design which you must be aware of.

If you won't use the SENSE function you must put some tin on J1 and J2.

ok

removed BD139 and  c9, jumpered R10, tinned J1 and J2, removed R11

voltage out is now 8.27v

still much too low

[peranders]

If you measure the voltages at the opamp inputs and they are the same, you must change the gain. Have you put the used resistor values into the formula? Please note which resistor is R8 and which is R9.

If you have more resistance on R9 than R8 the gain will be less than 2.

R8 = 2.15k

R9 = 680R

[Keljian]

R9 and R8 isn't right. The gain forumla is Vout = Vref*((R8/R9)+1)

I see that you have chosen AD797. I have not yet tested it with this opamp but from what I know the regulator gets a bit more sensitive against capacitive load. AD825 is much better in this sense. Still if you have at least 50 mm wire to the load it will probably work alright.

right

Vref = 6.9 (due to the use of LM329

so
6.9 * ((2150/680) +1) = 28.68

[Keljian]

R8 and R9 are correct ( Just measured)

[peranders]

Do you also have 6.9 volts across R9? If not the regulator isn't working properly. Remember also 33 volts in.

[Keljian]

Do you also have 6.9 volts across R9? If not the regulator isn't working properly. Remember also 33 volts in.

I have 1.69v across R9 (with 32.2 v in)

[peranders]

How about pin 7 of the opamp? Pin 6?

Does the LED shine?

Do you have 6.8 volts across DZ1?

Do you have 0.7 volts between base-emitter of all transistors?

Remember that the pcb is 100% error free so check very carefully that each part is the right one and they are turned right also.

[Keljian]

led lights up

6.74v across DZ1

0.31v on one of the opamp pins, 9.7v on the other