#1854

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IMSAI Guy

Ай бұрын

Episode 1854
just a look inside
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Пікірлер: 32

@TheDevice9 Ай бұрын

Dave: "Turn the temperature down CAL". CAL 9000: "I'm sorry Dave, I'm afraid I can't do that".

@andymouse Ай бұрын

LOL !

@capriracer351 Ай бұрын

10:34 That is the cold junction compensation for the thermocouple input.

@ybe6655 Ай бұрын

I do like the construction. Nice and compact.

@tiagoferreira086 Ай бұрын

My guess about the relay mounting decision has to do with the contact current handling given that it will almost for sure control some power hungry heating elements or some motor like a heat or fluid pump depending on the application requirements, and all that current flowing in such tiny contacts would be for sure a failure point, they could have more robust connectors but it would increase complexity and cost and again another possible failure point. As a bonus the galvanic isolation from the contacts to the board is also much better, and also the modularity for ease of manufacturing and assembling, so that decision is a win win win

@KeritechElectronics Ай бұрын

Nice internal build, I like the interconnections and how they packed it all in such a small enclosure. The base is typical 11 pin used for 3PDT relays, very similar to octal tube sockets save for the number of pins.

@robinbrowne5419 Ай бұрын

I like the little temperature sensor on its own corner of the board 👍

@ovi_4 Ай бұрын

Nice industrial work there. Nice video as usual. Tnx. I'm thinking of a PID style temp controller (using a 1N4148 diode as the temp. sensor and some 0 crossing Optos + a triac) to modify a (450W hot laminator that can only reach 150 Degrees celsius max and the temp control is all over the place ) so it can reach a steady 200 degrees Celsius for a PCB making application (the toner transfer method).

@keithwhitehead4897 Ай бұрын

Different models can use either the relay PCB or a SSR drive PCB

@jerril42 Ай бұрын

Attempt 3. There are square LEDs available on-line, careful there there are a lot of rectangular ones in a search.

@AttilaAsztalos Ай бұрын

A naive designer might think that a temperature sensor measures the temperature of the air surrounding the capsule. A designer who ever used one learns very quickly that what you actually measure is the temperature of the pins of your sensor, a.k.a. the temperature of the copper pads it is soldered to. It's up to you to try to bring that closer to that of the environment and away from all the other things pumping heat into your PCB and your ground plane - much the way they did here...

@misterhat5823 Ай бұрын

I bet that 60Hz transformer cost as much as the rest of the components combined.

@shagreobe Ай бұрын

We use 5 or 6 different type/brands of temp controllers, and I bring all the bad ones home to either try to fix or strip for parts or just play around with. Each type is different, but really kind of the same

@gorak9000 Ай бұрын

What's the percentage of failed ones that just need some new caps in the power supply? Like 90%? And I bet the other 9% is relay contact failures, and 1% fails in something else

@jj74qformerlyjailbreak3 Ай бұрын

I blame, taking things apart, for the knowledge I've acquired over the oast 4 years. I just finished my 2' * 2' LED probect. Its now a BIG 5050 Addressable LED from old drop ceiling light. Just need to favricate the 4 aluminum paws for the PCB piece of plywood footorints. 😂😆

@bborkzilla Ай бұрын

"CAL" 9000? LOL - "I'm sorry Dave, I cannot set that temperature."

@jspencerg Ай бұрын

I like the idea of using a pid controller. I want a multistep controller for my tempering and reflow oven. What multistep controller uses pid control? I've read a lot of product descriptions, but have not found such a device.

@IMSAIGuy Ай бұрын

github.com/UnifiedEngineering/T-962-improvements is the firmware I use in my reflow

@MrRezashokouhi Ай бұрын

Easy to replace relays ... I like that!

@staviq Ай бұрын

It would be super cool if you could reverse engineer the thermocouple preamp section and post a schematic I saw on signal path, a very sensitive micro-ohm meter which used seebeck effect compensation and I was thinking about making one myself, and this would be super helpful :)

@gorak9000 Ай бұрын

I think thermocouples generate a tiny current depending on which dissimilar metals are the junction (the "type" of the thermocouple) and the temperature. They're not resistive devices

@staviq Ай бұрын

Correct. However this tiny voltage effect always exists, for example when your resistor leads and the ohmmeter clips are made of different metals, and if you want to measure very small resistances ( of something other than a thermocouple ), that tiny voltage starts to skew the measurement, so high end lab equipment ( volt/amp/ohm meters ) actually account for that by measuring the Seebeck voltage and subtracting it from the measurement, to increase precision. If you want to measure resistances below 1mohm, the Seebeck effect can mess with the measurement by tens of %. So basically I meant adding "thermocouple-like" compensation to an ohmmeter, not measuring the resistance of a thermocouple to get temperature.

@CoolStuff.. Ай бұрын

cool

@frankowalker4662 Ай бұрын

I'm a big fan of transformer PSU's. Switch-mode PSU's are'nt as reliable.

@misterhat5823 Ай бұрын

I wonder what the analog switch is for?

@blahblahblahblah2933 Ай бұрын

My first thought would be to provide multiple channel input to a single input ADC or comparator.

@gorak9000 Ай бұрын

@@blahblahblahblah2933 I think to get an absolute reading from a thermocouple, you always compare the current in the measurement junction to the current in a reference junction that you know the temperature of, so the analog switch could be to switch the ADC between the external measurement thermocouple and the internal reference one.