Remolon

Left Channel done

A SMD Dynalo. It is a modular double monophonic one, comprises four small PCBs: two for audio and two for the corresponding power supply.

A phono preamplifier with the LME49720. Testing a channel before ordering PCBs

I had the incident yesterday. The Banned Screen appears before to have the chance to introduce the data to login, I had a previous one in a different place, connected to a different net. So, it appears to be random and not related to the person or the point of connection.

Not exactly. Suppose we need 100R. Paralleling two 200R: 200R + .5% = 201, in parallel 100.5R, exactly 100R + .5%, Although with less probability of the maximum error.

why not, if the TO126 body is non conducting pastic?

would be a significative difference in heat transfer turning upside down the BJT and using the other face for cooling?

I think that 2 mm paths for the output transistors and 1 oz. copper is more than enough for the current handled by the Dynalo.

This is the Dynalo PCB I am using. I ordered them from Elecrow. They are 94mmx74mm, 2 layer,1 oz. copper and 1,6mm thick. The price for 10 is 14USD plus shipping, and the quality is good enough.

Just permuting 500R and 1K the maximum Iccs does not change and the minimum is lower. For a LED with Vf=1.8V: Imax= 3.6mA and the minimum of 2.52mA change to 1.31mA

Thanks Kerry

The current source/sink LED (859-LTL-4213) has Vf=2.1V. So, with R1/R4 of 500R, the minimun possible current is 3.15mA. I'm using 1K to regulate the current from 1.65mA and up. For the gain, I'll try 20K for R52/R56 and 10pF for C1/C3. Do you think that these changes are appropriate?

I don't know if it is too complicated to do (or even convenient) but I believe that moving the heatsinks, and the transistors, to the other side of the PCB would improve the cooling.

JBC CD-1BD. I alsol keep the previous (analog) model that I have been using for more than 20 years with no problems.

I don't know if this is a solution but there are dielectric liquid coolants, such as silicones, used in the electric and electronic industry, as an alternative to water.

Thanks Jim. Interesting and well documented information, as usual.

I measure at the cathode resistor, to control the point of operation of the valve, but this is a good tip. Thanks.

Thanks, your response allows me to order the PCB with more confidence.

Thanks Jim for all the writing about the CCS. I'm planning to use this CCS to feed a triode of a ECC99 tube. B+ of 350VDC Q1 10M45S (TO-220) Q2 DN2540 (TO-92) Ra 133R, to provide 10mA Q1 is a TO-220 with a heatsink but DN2540 would be a TO-92 because I believe it will dissipate only a few mW and does not need a heatsink, what simplifies the PCB. I will appreciate any comment or correction.

I still keep the slide rule, the HP11C and two posterior models but unfortunately I don't keep the HP35, the first HP that I had.

Pins 2 and 7 are connected to the grid. Seeing the continuity with a multimeter will identify both and help to deduce the rest

I am curious, has someone measured the distortion of the 6S4A on the KGST?

There are two negative reasons: I am not interested in having an extra KGST set, and, secondly, I live in Spain and this will increase the final price because of the shipping cost if no most of the interested people live in Spain, or at least in the EU, and because the PCBs coming from China have to pay custom duties in Spain.

It was intended as a small contribution for a informed decision.

I have been looking at Seeed (lately, I order from them) and the quote that I get for 15 units, 15cmx15cm maximun, 2 layer, 2 oz. is 121.23$, and 175.06$ for 30. So the total amount for 30 amp boards plus 15 PSU is 296.29$ (plus shipping). That is 19,75$/set of 2 amps + 1 PSU boards for a order of 15 sets.