I’ve just received a bunch of bolts, nuts and washers from Rawcnc. 1.3kg of stuff to be precise. Very cheap and very good service. Especially considering that it’s a small one man business. It’s the same guy that makes the Raw 1.5 CNC mill. A mill I wish I had the space (and my better half’ s permission) to get.
I’ve got different stepper motor drives on the way, HY-DIV168N-3.5A.
I’ve also received the raw material for the Z-axis plate/spindle mount plate.
And then there’s the MR12(correct name?) rails and some MGN12H carriages.
I’m not sure I’ll use those exclusively for the X-axis, I may use one rail on top of the upper 2080 profile and use 12mm rods with bearingblocks on the front of the 2080 profiles. I.e. using the 12mm rail and carriage to reduce vertical stress on the 12mm rods/bearingblocks.
It’s the kind of decision I’ll make having all parts in front of me as what works “in your head” may not be the best idea in reality.
Well I got the Elna ROA Cerafine 1000uF/10V output capacitors and the extra 33R Takman resistors I needed today.
Thanks to Hifi-collective.
I put the 33R Takman resistors in parallel with the ones already there for 16.5R to raise the bias a bit.
I populated the output capacitors and put Wima MKS2 4.7uF in parallel with them.
With a 9V battery as power supply, I got 6.97mA with the 16.5R and 5.30mA with the 33R bias resistors. I only got a 0.01mA between the 4 output pairs, I consider that an ok result.
Next is to test DC-offset with a resistive load, as the output capacitor makes accurately measuring that without a load more or less impossible.
That’ll have to wait until I get one of the smps supplies I’m waiting for. One 19V/3.6A (for use with a step-up converter) and one 22V/1A. I don’t know if 1A is enough for the DAC/headamp combo as I think the 24V/1A got a little warm. There’s of course no telling if the 24Vdc supply actually is 1A as I got it off eBay years ago to power B+ of an ECC86 based DAC output stage, and for that it worked fine.
Btw, I haven’t forgotten about the guy asking me for a couple of matched pairs of the BF862’s, I feel guilty not checking what I have every time I see those little jfets.
In order to get the most of my CNC router/engraver, I came to realize that I needed to learn some CAD software to build it to the best of my abilities. Then when built, I’ll have immense use of the CAD knowledge and I will then need to learn some CAM software.
I have tried, very briefly, to use CAD software in the past. Not having a clue what I did, I gave up very quickly.
The other day I stumbled across a tutorial about the entirely free (for open source use) and entirely cloud-based Onshape, it runs from your browser (like chilipeppr) though edge and internet explorer aren’t advised by onshape.
So, when I have some parts done that I’m happy with, I’ll get some of them 3D-printed as I THINK 20mm thick of the most rigid filament would be strong enough for this project.
I can really recommend Onshape as 1, it’s free 2, there’s plenty of parts available made by others and 3, the tutorials and support is great as far as I have experienced thus far.
While I’m waiting for the 1000uF/10V Elna ROA Cerafine output caps and the extra 33R Takman resistors, I re-wired the ALPS pot with silver in PTFE on the output side.
Hifi-collective sent the parts out this morning, so now it’s up to Royal Mail and Swedish Mail as to when they arrive. I’m hoping they come before the weekend.
I have a couple of the cheap ES9023 boards.
I replaced some components on one of them this morning. I have no idea what was used originally, but considering what they sell for, I doubt they were the greatest of parts. I used AVX PPS for the 4n7 output capacitors, Panasonic PPS for the 100nF and Murata X7R for the 1uF as I didn’t have C0G/NP0 or PPS of that value in that size (0805).
So, I made a wiring error when wiring up the power supplies for this project. It seems, the only, fatality of that error was the CS4397 IC.
I feel bad as it was gifted to me. I have a replacement ordered.
When I did test it all with the correct voltages all around, I got too much DC-offset on the headamp output. As this design has a output capacitor, the problem could just be a lack of load ie a resistor between each channel and gnd. Since I needed to shorten much of the wiring anyway, I took the opportunity to separate gnd-in to the ALPS pot from the gnd going from that to the headamp.
While having the thing apart, I removed the Elna Silmic II 100uF/25V and moved the Elna ROA Cerafine 470uF/25V from the output to the input PS spot. I’ll replace the output cap with a 1000uF/10V Elna ROA Cerafine.
I’ll also raise the bias on the jfets from about 8mA to around 10mA.
More to follow.