Hello world.
My name is Gary and I have been interested in electronics for many years but only dabble in the subject.
I would like to get to the point where I can better diagnose issues with retro computers, understand schematics and more.
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Welcome @institches! I’m a big fan of retro computers and retro video game consoles. I miss the days when computers came with their own schematics. Looking forward to following along in your build log!
@jonthomasson Thanks Jon. It just happens that the computer I’m dealing with at the moment has a heap of really good schematics - all except the power supply. I’m planning on replacing the power supply capacitors but I’m curious to measure the noise before and after cap replacement, just out of curiosity.
That sounds like a fun project. I’ve got a non working C64 and an old CGA monitor I want to try and fix. It may be a similar situation where some of the electrolytic caps are blown.
I’ve also got non working C64s and there are several chips in them that run very hot. It’s a good idea to put heat sinks on them.
I sent off my order for Shine on you Crazy Kicad boards to Oshpark last night and ordering the parts today. I’m hoping this will partly provide inspiration to my 5 year old niece who loves blinky LEDs.
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Awesome! Looking forward to some pics or videos of you completed boards!
Sent off Getting To Blinky order to Ohspark today and ordered parts. Looking forward to building the boards.
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My Shine On boards arrived yesterday. I’m going to have a go at trying to solder with my dominant arm in a sling. It could be interesting.
I have assembled my Shine On and Getting to Blinky boards and I really enjoyed the process. All went well and I’m grateful for my magnifying head-set.
Moving on to the CE header project now.
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My CE Header board is currently on order at Ohspark and I’m working my way through the Sensor Board. I also signed up for the apprenticeship program here and am looking forward to doing the projects.
I’m especially looking forward to the Current Sink or Swim project as I would like to test battery capacity.
I have a collection of old HP calculators that I often rebuild the ni-cad battery packs. I ordered some batteries from China and went to all the trouble of fitting them into the battery carrier pack and found the capacity seemed very low. I know I could do rough tests by using a resistive load but I would like to apply a constant current to get an accurate reading.
Another project I’m thinking about is a device that can turn on my PC via the internet by just shorting the power connection momentarily. This is so I can wake up the PC remotely, allowing me to remote on to it.
I ordered the Analog Discovery 2 with my apprenticeship subscription and just took the $75USD freight charge on the chin. I just received a call from FedEx saying they want to charge me import duties and GST (goods and services tax) on it 
The law here is anything imported that comes to more than $400NZD gets slapped with these duties.
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Submitted my sensor board to Oshpark so I can’t wait to get it back and start building it!
Congrats Gary! It looks like you have some awesome projects lined up. I can’t believe how steep the import duties are where you live!
The AD2 was $15 over the threshold of $400 for the taxes but the actual taxes weren’t too high so it worked out okay. Even with the freight and taxes, it was still cheaper than buying it from Element14 and the like.
The Analog Discovery 2 arrived today which is exciting. I tried out the scope by connecting it to an HP calculator AC adapter which my multimeter measures an output voltage of 12V AC.
When I measure it on the scope I get a reading of +17V to -17V. The only thing I can put that down to so far is my multimeter is reading the RMS value and the scope is not?
Ah, so that’s likely the un-loaded voltage of the transformer inside of the adapter. Those are usually pretty loosely spec’d in the first place (10% of the specified 12V). But transformers’ voltage normally drop when you start to pull current out of them into a regulator.
Correct! I assume the voltage measurements from both the voltmeter and scope were with the same or no load. Such an AC adapter probably has a very low current rating anyway so I would expect very little difference between loaded and unloaded voltage measurements. 12V is indeed the RMS of 17VAC.
Vrms = Vp / √2 = 17 / 1.414 = 12.02 Vrms
or
Vrms = Vp-p / 2√2 = 34 / 2.828 = 12.02 Vrms
Good point good point. Guess we’ll have to ask that Gary tests it out while loaded too now 
I’ll connect the power supply to the charger with battery installed tonight.
I measured the voltage with the multimeter and the scope while the power supply was not under load.
Thanks @1.21Gigawatts - I did the calculation for the 17V peak last night but I didn’t think to calculate the peak to peak.