858D++ Block Diagram

config.toml

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content/posts/2018-07-10-Saike-858DPP-Block-Diagram.md

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+---
+title: "Saike 858D++ - First Block Diagram"
+date: 2018-06-25T08:00:00+02:00
+author: eNBeWe
+type: post
+categories:
+  - Allgemein
+  - Bastelkram
+tags:
+  - 858D
+  - DIY
+  - Arduino
+---
+
+After a short break, here is the first part about the redesign of the Saike 858D rework station ([Overview][1]).
+
+Let's talk about a rough block diagram for the new design.
+
+<!--more-->
+
+[![Saike 858D++ Block Diagram](/posts/images/858D/Concept-New-Design_V1.png)](/posts/images/858D/Concept-New-Design_V1-big.png)
+
+Let's have a look at the general structure and first follow the path of the power supplies.
+Twe build a mains powered device so we start with that at the top left.
+The mains power is fed into the heater control circuit as well as a 24V switch mode power supply,
+which I will use to replace the transformer.
+
+The 24V power supply is connected to the fan control circuit and another switch mode supply,
+this time providing a 5V rail.
+The 5V supply is used for an Arduino board, 
+which will be plugged on the main PCB. I have not yet decided which model I want to use,
+but it will probably be one of the Pro Micro or Nano boards I have lying around.
+Additionally, the 5V supply is used for the other logic level components,
+like the display and the sensors.
+
+The Arduino is connected to the heater and fan control circuits,
+both regulated through some form of PWM. 
+The heater control will use more or less the same design as the original,
+regulating the heater through a optocoupled triac.
+The fan control will use regular PWM to switch a power mosfet that
+can in turn regulate the fan supply.
+Additionally, there will be a form of monitoring of the fan speed.
+I am currently pondering which way I want to go there.
+
+The display will be replaced by two 7-segment displays with 4 digits each.
+The displays are controlled by a MAX7219 IC,
+which is connected to the Arduino through SPI.
+
+The sensor inputs from the handle sensor and the thermocouple
+are fed into the Arduino directly and are used in the control loop.
+
+That's about it. There is still some uncertainty about some desin points,
+but I am feeling confident that this should, at least roughly, work.
+
+
+ [1]: {{<relref "2018-06-20-Reverse-Engineer-a-Saike-858D.md">}}
+