{"id":7619,"date":"2026-05-13T02:27:43","date_gmt":"2026-05-13T02:27:43","guid":{"rendered":"https:\/\/41j.com\/blog\/?p=7619"},"modified":"2026-05-13T02:27:45","modified_gmt":"2026-05-13T02:27:45","slug":"inheco-96-chick-brooder","status":"publish","type":"post","link":"https:\/\/41j.com\/blog\/2026\/05\/inheco-96-chick-brooder\/","title":{"rendered":"INHECO 96 Chick Brooder"},"content":{"rendered":"\n

Overview<\/h2>\n\n\n\n

The Inheco Control 96 is an OEM unit built around a Watlow Series 96 PID controller<\/strong> and a Watlow LSTW driver module<\/strong>, housed in an Inheco-branded chassis. Originally designed for TEC\/Peltier temperature control in laboratory equipment (e.g. the Inheco CPAC Ultraflat for heating Eppendorf tubes), it can be repurposed as a general-purpose temperature controller.<\/p>\n\n\n\n

This writeup documents repurposing one such unit to drive a Kotatsu heater element<\/strong> (~100V rated, operated at 30\u201340V) as a brooder heater for day-old chicks. The unit was acquired second-hand and arrived with a PIC microcontroller attached to the RS232 port and the controller in a misconfigured\/locked state.<\/p>\n\n\n\n

Reference also: 41j.com Inheco Control 96 Notes<\/a> \u2014 confirms the LSTW is an undocumented OEM module, likely an H-bridge in the original TEC application, but in single-output configurations acts as a simple DC power switch.<\/p>\n\n\n\n

\n\n\n\n

Hardware<\/h2>\n\n\n\n

Watlow Series 96 PID Controller<\/h3>\n\n\n\n
    \n
  • 1\/16 DIN panel mount PID controller<\/li>\n\n\n\n
  • Universal input (thermocouple, RTD, process)<\/li>\n\n\n\n
  • 4 outputs (configuration dependent on model)<\/li>\n\n\n\n
  • RS232 serial communications on output 4 terminals (19, 20, 21)<\/li>\n\n\n\n
  • Keys:\u00a0\u25b2 Up<\/strong>,\u00a0\u25bc Down<\/strong>,\u00a0\u221e Home\/Infinity<\/strong>,\u00a0\u21ba Advance\/Cycle<\/strong><\/li>\n\n\n\n
  • Firmware version on this unit:\u00a0r7dL<\/strong>\u00a0(visible in DIAG menu)<\/li>\n<\/ul>\n\n\n\n

    Watlow LSTW 1.5 Driver Module<\/h3>\n\n\n\n
      \n
    • Undocumented OEM module, not available on Watlow website<\/li>\n\n\n\n
    • 8-terminal connector block<\/li>\n\n\n\n
    • Functions as a\u00a0DC power switch<\/strong>\u00a0(not a true SSR)<\/li>\n\n\n\n
    • Contains an\u00a0IRF5305 P-channel MOSFET<\/strong>\u00a0(55V, 31A rated) as the main switching element<\/li>\n\n\n\n
    • Protection diode across input: originally\u00a0B13 Schottky<\/strong>\u00a0(30V, 1A \u2014 undersized)<\/li>\n\n\n\n
    • Status LEDs:\u00a0GRUN<\/strong>\u00a0(green) = control input active,\u00a0ROT<\/strong>\u00a0(red) = output switching on<\/li>\n<\/ul>\n\n\n\n

      LSTW Terminal Pinout (as determined empirically)<\/h4>\n\n\n\n
      Pins<\/th>Function<\/th><\/tr><\/thead>
      1\u20132<\/td>Unknown \/ unused in this config<\/td><\/tr>
      3\u20134<\/td>Output to load (heater)<\/strong><\/td><\/tr>
      5\u20136<\/td>Control input from Watlow 96<\/strong> (24V DC signal)<\/td><\/tr>
      7\u20138<\/td>Connected to Watlow 96 rear center terminals (power\/common)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

      The LSTW passes the supply voltage through to the load when the control signal is active \u2014 it does not<\/strong> have a separate mains input. Supply voltage = output voltage.<\/p>\n\n\n\n

      Kotatsu Heater Element<\/h3>\n\n\n\n
        \n
      • Rated 100V AC<\/li>\n\n\n\n
      • Operated at 30\u201340V DC (sufficient for brooding temperatures)<\/li>\n\n\n\n
      • Connected to LSTW output terminals 3\u20134<\/li>\n<\/ul>\n\n\n\n

        Thermocouple<\/h3>\n\n\n\n
          \n
        • Type J (blue\/red wire, European IEC colour code)<\/li>\n\n\n\n
        • Connected to Watlow 96 Input 1 terminals<\/li>\n\n\n\n
        • Polarity sensitive \u2014 blue wire to negative terminal<\/li>\n<\/ul>\n\n\n\n
          \n\n\n\n
          \n\n\n\n

          Watlow Series 96 \u2014 Key Navigation<\/h2>\n\n\n\n
          Action<\/th>Key Sequence<\/th><\/tr><\/thead>
          Home Page<\/td>Press \u221e<\/strong> briefly<\/td><\/tr>
          Operations Page<\/td>Press \u25b2 + \u25bc<\/strong> together (~3 sec)<\/td><\/tr>
          Factory Page<\/td>Hold \u221e + \u21ba<\/strong> together for 6 seconds<\/strong><\/td><\/tr>
          Setup Page<\/td>Hold \u25b2 + \u25bc<\/strong> together for 6 seconds<\/strong><\/td><\/tr>
          Enter a menu<\/td>Press \u21ba<\/strong><\/td><\/tr>
          Change value<\/td>\u25b2<\/strong> \/ \u25bc<\/strong><\/td><\/tr>
          Confirm value<\/td>Press\u00a0\u21ba<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

          Some config settings appeared to be locked out at first. I’m not sure if I was just misunderstanding the config system or if I actually fixed this. There was a PIC connected to the RS232 input on the Watlow 96, this seemed to be processing a signal from a knob on the front of the unit. I disconnected this.<\/p>\n\n\n\n

          \n\n\n\n

          Configuring the Thermocouple Type<\/h2>\n\n\n\n

          Accessing CIN1 (Calibration Input 1 Menu)<\/h3>\n\n\n\n
            \n
          1. Enter Config Page: hold\u00a0 \u25b2+\u25bc for 6 seconds (it changes to one menu after 3s then again)<\/li>\n\n\n\n
          2. Press\u00a0\u25bc<\/strong>\u00a0to navigate to\u00a0CIN1<\/strong><\/li>\n\n\n\n
          3. Press\u00a0\u21ba<\/strong>\u00a0to enter<\/li>\n\n\n\n
          4. Set the thermo couple type to H to K-type and J for J-type.<\/li>\n<\/ol>\n\n\n\n
            \n\n\n\n

            LSTW Diode Failure and Repair<\/h2>\n\n\n\n

            What Happened<\/h3>\n\n\n\n

            When attempting to supply ~40V DC to the LSTW input (to drive the Kotatsu heater at sufficient power), the protection diode B13<\/strong> failed with visible smoke.<\/p>\n\n\n\n

            Root Cause<\/h3>\n\n\n\n

            The B13 is a 30V, 1A Schottky diode<\/strong> \u2014 it is connected across the input terminals as a flyback\/protection diode. Supplying 40V exceeded its 30V rating, causing it to fail.<\/p>\n\n\n\n

            The main switching MOSFET (IRF5305<\/strong>, P-channel, 55V\/31A, TO-220 package) survived.<\/p>\n\n\n\n

            Repair<\/h3>\n\n\n\n

            The blown B13 was removed. Unit was tested without it \u2014 functional short-term since the MOSFET is not switching at high frequency in this application, so flyback spikes are minimal.<\/p>\n\n\n\n

            Replacement diode found by scavenging:<\/strong> A D2S58<\/strong> Schottky diode was recovered from scrap PCB.<\/p>\n\n\n\n

            D2S58 specifications: 80V, 2A<\/strong> \u2014 significantly better rating than the original B13 and well suited for this application.<\/p>\n\n\n\n

            Installation:<\/strong> Cathode (stripe) to positive<\/strong> input terminal. Solder across input terminals in same orientation as original B13.<\/p>\n\n\n\n

            \n

            The D2S58 replacement is an improvement over the original B13. If sourcing a new part, any Schottky diode rated \u226550V, \u22651A<\/strong> is suitable (e.g. 1N5819 at 40V is marginal; prefer SS34, 1N5822, or similar at 40V+).<\/p>\n<\/blockquote>\n\n\n\n

            \n\n\n\n

            Final Working Configuration<\/h2>\n\n\n\n
            Parameter<\/th>Value<\/th><\/tr><\/thead>
            Thermocouple type<\/td>J type (J<\/code>\u00a0in CIN1)<\/td><\/tr>
            Thermocouple wiring<\/td>Blue = negative, Red = positive<\/td><\/tr>
            LSTW control signal<\/td>24V DC from Watlow 96 Output 1 (terminals top 3-pin block)<\/td><\/tr>
            Supply voltage to LSTW<\/td>~40V DC (Rigol DP832)<\/td><\/tr>
            Heater<\/td>Kotatsu element, connected to LSTW output terminals 3\u20134<\/td><\/tr>
            LSTW protection diode<\/td>D2S58 (scrap), across input, cathode to positive<\/td><\/tr>
            Setpoint<\/td>Set to desired brooding temperature (e.g. 35\u00b0C for day-old chicks)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
            \n\n\n\n

            Operational Notes<\/h2>\n\n\n\n
              \n
            • The\u00a0GRUN LED<\/strong>\u00a0on the LSTW indicates the 24V control signal is present and active<\/li>\n\n\n\n
            • The\u00a0ROT LED<\/strong>\u00a0indicates the output is switching (heater powered)<\/li>\n\n\n\n
            • If ROT is lit but no heat: check supply voltage is connected to LSTW and heater is connected to output terminals 3\u20134<\/li>\n\n\n\n
            • ERR4 on the Watlow 96 = open sensor (thermocouple disconnected or broken) \u2014 check wiring at terminals 5, 6, 7<\/li>\n\n\n\n
            • The controller PID will modulate output to maintain setpoint \u2014 allow time for auto-tuning to stabilise temperature control<\/li>\n\n\n\n
            • A few degrees offset between reading and actual is normal with replacement thermocouples \u2014 a calibration offset can be added in the IN1 menu if accessible<\/li>\n<\/ul>\n\n\n\n

              <\/h2>\n","protected":false},"excerpt":{"rendered":"

              Overview The Inheco Control 96 is an OEM unit built around a Watlow Series 96 PID controller and a Watlow LSTW driver module, housed in an Inheco-branded chassis. Originally designed for TEC\/Peltier temperature control in laboratory equipment (e.g. the Inheco CPAC Ultraflat for heating Eppendorf tubes), it can be repurposed as a general-purpose temperature controller. This writeup documents […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1],"tags":[],"class_list":["post-7619","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1RRoU-1YT","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/7619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/comments?post=7619"}],"version-history":[{"count":1,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/7619\/revisions"}],"predecessor-version":[{"id":7620,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/7619\/revisions\/7620"}],"wp:attachment":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/media?parent=7619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/categories?post=7619"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/tags?post=7619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}