Hacking a food dehydrator 🍇

[807]

If you disconnect one of the diodes in the joint (red circle), the overall power will be halved, also the fan will run more slowly...

The rectifiers are only for the motor, not the heating element. Disconnecting one rectifier will make the motor run more slowly but the heating element will still be running at approximately the same power, which risks overheating with the lower airflow.  In practice there will be a small change in power as the motor effectively shunts a small section of the heater element, so drop across that section will increase on one half cycle with the rectifier removed.

That's why I was confused by DavidAlfa's reply. I was scratching my head trying to make sense of his suggestion to remove one of the diodes. All I could see happening was burning out the element quicker due to reduced air flow.

[807]

@Angel_heart...you said in your first post that you wanted to deactivate the heating system, but leave the fan. Is that actually what you still want to do, or do you still want to keep the heating element but reduce the temperature?

[RJSV]

Angel_Heart:
   I would tend to separate the two tasks, especially OK with doing that, on a custom one-off, as you aren't looking for manufactured in mass, saving pennies here and there.
   For safety, figure out if you can enclose a wall wart supply,...but INSIDE the safe enclosure.  That way at least the dangerous mains voltage has no path outside the enclosure.
I'm thinking, like most of us, 12 VDC is typical light weight computer fan, but is yours pushing a lot more air ? Like, is it very noisy ? Looks like maybe 32 VDC from reading the other posts. ?
   If a lower air flow is OK, how about pulling out that fan, (a hassle, I know).  Replace with 12 VDC fan ?
And then keep the wall wart DC supply inside the safety enclosure.  Also consider if there is an interlock, protecting fingers (small loved ones might be in house too).  Opening the lid should shouldn't be dangerous to fingers.
  Sounds more and more bodgy the more I think about...EU safety regulations, including fire hazard avoidance.  Purchase insurance ?

[Zero999]

Do you want to keep the fan the same speed? If so, you'll need to power it from a small transformer and rectifier, or DC power supply.

The heating element can be connected in series with a lamp dimmer, to adjust the temperature.

The motor and heater must still be connected so the heater can't be run, without the fan.