Search found 79 matches

by Studioalethea
Mon Mar 30, 2020 1:52 am
Forum: Music Tech DIY
Topic: CD4024 Reset (Clock Debug)
Replies: 2
Views: 69

Re: CD4024 Reset (Clock Debug)

UPDATE: I just had some grounding issues. All good now! It helped to ground the two unused pins of the 4024 counter.
by Studioalethea
Sun Mar 29, 2020 4:46 pm
Forum: Music Tech DIY
Topic: CD4024 Reset (Clock Debug)
Replies: 2
Views: 69

CD4024 Reset (Clock Debug)

Hey all - Debugging my Fonitronik simple clock and am curious how the Reset pin works. Does it reset on high or low? UPDATE: I found this in the datasheet... it just wasn’t where I expected it. I pulled the reset connection entirely, and the circuit is just being very erratic. It sometimes works, so...
by Studioalethea
Thu Mar 26, 2020 11:50 am
Forum: Music Tech DIY
Topic: EasyEDA and Silkscreens
Replies: 11
Views: 220

Re: EasyEDA and Silkscreens

Hello CadFriends! I am pretty new to PCB design, so in quarantine I have been working on a prototyping board design. I want to silk an image that in the Gerber, the silkscreen covers the plated holes. Obviously, it's NOT ideal to make a silkscreen that overlays the holes or exposed copper traces BU...
by Studioalethea
Sat Mar 21, 2020 1:24 am
Forum: Modular Synth General Discussion
Topic: What does rock solid build quality mean to You?
Replies: 22
Views: 750

Re: What does rock solid build quality mean to You?

“Rock solid” for me means two things that are related but not identical. I usually use the term to mean dependable. Like an SM58. It always works. It’s simple but also well-built. You can throw it against a wall, pick it up with a dented grill and put it on a vocalist. It is dependable BECAUSE it is...
by Studioalethea
Sat Mar 21, 2020 12:06 am
Forum: Music Tech DIY
Topic: EasyEDA and Silkscreens
Replies: 11
Views: 220

Re: EasyEDA and Silkscreens

Synthiq wrote:
Fri Mar 20, 2020 10:25 pm
EasyEDA has forum for users so maybe you can ask there if they can help you as well.
Have now posted there, too. Thanks for the suggestion!
by Studioalethea
Fri Mar 20, 2020 11:52 pm
Forum: Music Tech DIY
Topic: EasyEDA and Silkscreens
Replies: 11
Views: 220

Re: EasyEDA and Silkscreens

If it's an obvious problem many if not most PCB fabs will automatically clear the screen from the pads for you. Sometimes when you don't want them to. It's not in their best interest to send you something with such an obvious mistake. But that doesn't mean they will do it. Just that they usually do...
by Studioalethea
Fri Mar 20, 2020 10:11 pm
Forum: Music Tech DIY
Topic: EasyEDA and Silkscreens
Replies: 11
Views: 220

Re: EasyEDA and Silkscreens

I use KiCad and it has an option "Exclude pads from silkscreen" so maybe you can check if EasyEDA has a similar option. I'm not seeing anything like that in EasyEDA. Also having the same issue ordering from PCBWay of not getting a clear answer either way. I'm trying to see if I can import the Gerbe...
by Studioalethea
Fri Mar 20, 2020 5:02 pm
Forum: Music Tech DIY
Topic: EasyEDA and Silkscreens
Replies: 11
Views: 220

Re: EasyEDA and Silkscreens

I don't know the answer to your question, but it is possible EasyEDA automatically removes the silkscreen where there is an opening in the solder mask before generating the Gerber. You can look at the generated Gerber files to see if this is the case. The Gerber definitely shows it covered BUT in E...
by Studioalethea
Fri Mar 20, 2020 1:28 pm
Forum: Music Tech DIY
Topic: EasyEDA and Silkscreens
Replies: 11
Views: 220

EasyEDA and Silkscreens

Hello CadFriends! I am pretty new to PCB design, so in quarantine I have been working on a prototyping board design. I want to silk an image that in the Gerber, the silkscreen covers the plated holes. Obviously, it's NOT ideal to make a silkscreen that overlays the holes or exposed copper traces BUT...
by Studioalethea
Tue Mar 17, 2020 12:56 pm
Forum: Music Tech DIY
Topic: Precision Multimeter Round-Up
Replies: 7
Views: 254

Precision Multimeter Round-Up

Hey all! I have just been made aware that my multimeter is insufficient for transistor and resistor matching with any repeatable results. SO, what you all got? Seems like electricians really stand by the Fluke 87V. Flir popped up for me when scaling up some other models like the Extech Ex330 -- what...
by Studioalethea
Mon Mar 16, 2020 9:40 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

Those specifications are actually slightly better, but it's still a cheap low-end meter. Unfortunately you get what you pay for with test equipment and a $25 meter is just not that good. For comparison's sake, the meter that I'm currently using retails for $400. You really should get a decent quali...
by Studioalethea
Mon Mar 16, 2020 7:29 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

What are the specifications of the second meter? Take care, Doug Worse than the first? Not sure... Etekcity MSR-A600 Safety/Compliances: IEC61010, CAT.II 600V over voltage and double insulation Display: Maximum display 1999 Range selection: Auto ranging Overload display: Display OL Measurement Spee...
by Studioalethea
Mon Mar 16, 2020 7:09 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

LED-man wrote:
Mon Mar 16, 2020 6:40 pm
AstroAI DMM specs.
DC Voltage: 600mV/6V/60V/600V ±(0.8%+3), 1000V (1%+5)

in Germany we say:
Wenn du misst, misst du Mist.
When you measure, you measure shit.
I have been using two different DMMs and been getting similar results, but what do you recommend instead?
by Studioalethea
Mon Mar 16, 2020 6:31 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

You did clean the flux off right? The easiest thing to try would be to swap two closely matched transistors between the two sockets and see how the number changes. That will tell you how closely matched your 100K resistors and the rest of the circuit is. If you do build another one maybe include th...
by Studioalethea
Mon Mar 16, 2020 4:16 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

My luck has turned... I can’t get repeatable numbers any longer. I was waiting 2-3 minutes for each one and really got some settled numbers that were repeatable. But now the couple of really great pairs I had are not as close. I was using a reference transistor and separating my the difference. Then...
by Studioalethea
Sun Mar 15, 2020 8:15 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

I completely agree about removing the flux. That stuff is hydroscopic, so it picks up moisture from the air over time and eventually starts acting like a high megohm value resistor. Blowing air on it could change the moisture content and be another cause of drift on such a sensitive circuit. I alwa...
by Studioalethea
Sun Mar 15, 2020 5:29 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

Our last batch from Mouser were pretty much all within 2mV and we could easily find matches up to 0.1 mV. Did you try covering your test jig? Take care, Doug A bit! See below. What’s your method? Do you do a quick pass with some other method? Or compare them all to and reference tranny and then com...
by Studioalethea
Sun Mar 15, 2020 5:07 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

Try putting the pcb on a piece of carpet and covering it with a small bowl so that there are no air currents around the transistors at all. Take care, Doug MAY be starting to get some better results... 1) I turned off the fan. 2) I unplugged any unused modules from my test bench. I only had another...
by Studioalethea
Sun Mar 15, 2020 4:25 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

Here is the underside.

Turning off the fan didn’t seem to help. Left a pair for 20 minutes and it was still swinging by 4mV at least
by Studioalethea
Sun Mar 15, 2020 2:44 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

Here is a closeup of the circuit itself.

3.9K resistor from positive power supply to the collectors. Bases tied together to ground. Measuring at emitters, preceding the matched 100k resistors to negative power supply.
by Studioalethea
Sun Mar 15, 2020 2:36 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

Any help would be lovely, thanks! What kind of meter are you using? Brand and model number? Should be able to get quite a bit closer than 1K with even a few 100K resistors.. Where did they come from? Post a pic or two of your test circuit setup. Is the fan blowing across the plane of the two DUTs? ...
by Studioalethea
Sun Mar 15, 2020 1:36 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Re: Inconsistent Transistor Matching Results

I am not a fan(!) of the fan method for transistor matching, I built my circuit in a small plastic box with tiny holes for the multimeter leads. Inserting the transistors with plastic tweezers and closing the cover of the box, then waiting a couple of minutes for stabilisation works very well and i...
by Studioalethea
Sun Mar 15, 2020 12:39 pm
Forum: Music Tech DIY
Topic: Inconsistent Transistor Matching Results
Replies: 31
Views: 328

Inconsistent Transistor Matching Results

Hey all! I built my Ian Fritz circuit for matching my NPN transistors, and I am struggling with my measurements. I matched the resistors to within 1k, so I didn’t install the optional trimmer (I.e. measured with my multimeter that one is 100.1k and the other is 100.2k). Is 1k tolerance sufficient? I...
by Studioalethea
Sun Mar 15, 2020 12:00 am
Forum: Music Tech DIY
Topic: Transistor Matching Circuit
Replies: 6
Views: 302

Re: Transistor Matching Circuit

I finally made it!

I matched the resistors to within 1k ohm— is that sufficient?

How long should you wait before moving on with the measurements? We’re looking for about 1mV difference right?
by Studioalethea
Sat Mar 14, 2020 8:10 pm
Forum: Music Tech DIY
Topic: Transistor Matching Circuit
Replies: 6
Views: 302

Re: Transistor Matching Circuit

Does the DPDT switch reverse the leads of the transistor? Anyone add the trimmer pot to keep from having to over spend time on the resistor matching?

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