Bud dryer - manicured to smoke in 3 days - Page 17

LoudBlunts · #**161** 06-13-2008, 02:03 PM

Welcome Back Al!!!!

Al B. Fuct · #**162** 06-13-2008, 02:27 PM

heh, thanks LB.

bula bula!

LoudBlunts · #**163** 06-13-2008, 02:45 PM

why is your thread closed?

Al B. Fuct · #**164** 06-13-2008, 03:08 PM

It had run its course. It was all about a 2-week rotation SoG grow- I covered that any number of times- and the thread turned into 'Ask Al B.' It got so long that people were not fully reading it anymore and I'd get the same questions over and over.

I might start a new thread one of these days, but I was putting too much of my day into it. We'll see.

LoudBlunts · #**165** 08-20-2008, 12:32 AM

Quote:

Originally Posted by Al B. Fuct

Hmm.

Keep in mind that there's a lot of wiggle room to improvise, but this is the basic kit:

* storage tub w/ lid (lid must seal tightly - or strips of foam rubber can be used to make seals for the lid edge)
* 80mm - 120mm fans x2
* 1/2" grid hardware cloth & open link chain for bud racks - or freestanding plastic racks which fit in the tub
* (240V version) 1.8k ohm, 25W power resistors, x6
* (120V version) 470 ohm, 25W power resistors, x6
* 300W (or better) incandescent light dimmer
* thermostat
* finned aluminum heat sink (this one's good - suits 80mm fans )

Unless you live in Australia, I don't think this would be practical. I reckon it'd cost about $AUD75-100 to ship a completed (if unassembled) dryer to Nth America or the UK.

I have seen bud dryers at some online hydro shops that are not dissimilar to mine, except these don't usually include a heater unit. They are priced INSANELY- $350- $1800! Totally wacky for a plastic box with a fan... If you were thinking of paying that much for a bud dryer, then it becomes practical for me to make you one... but I would be amazed if a gibbon with a few common tools could not make one in a couple of hours.

a few questions, al....

how big does the heat sink have to be?

what is the use for the light dimmer if the thermostat is capable of upping and downing of the temps? or do you wire both so you can control it through the thermostat? if not, is there a way to rig it so you can control it via the thermostat?

isnt there different wiring for the fan and the heating and cooling elements on the thermostat? im guessing if im using a fan with a filter on the end i would wire that up on the 'fan' option on the thermostat and have the button switched to 'on' not auto or off, correct?

Al B. Fuct · #**166** 08-20-2008, 01:47 AM

Quote:

Originally Posted by LoudBlunts

a few questions, al....

how big does the heat sink have to be?

oh crap, you would ask that.

I built my dryer with a heatsink that was on hand, not one that I selected for any particular performance characters.

So, let's go back to 1st principles and do some hypothesising. If the heat sink's too large, the resistors won't be able to put enough heat into the sink and air coming off it won't come up to 29C even when the resistors are at max power dissipation. If it's too small, the resistors will overheat because not enough heat is being taken off the heatsink into the airflow.

The sink I used is very similar in size and shape to this Jaycar unit (pictured above), which is 150mm x 75mm x 46mm.

Quote:

what is the use for the light dimmer if the thermostat is capable of upping and downing of the temps? or do you wire both so you can control it through the thermostat? if not, is there a way to rig it so you can control it via the thermostat?

I've put in the dimmer to smooth out the temp stability. IF I had calculated the ideal sized heat sink, the dimmer would not be needed. However, in my working example, the resistor bodies warm up very fast and will overshoot their max operating temp rating (80C on the R bodies) before the airstream comes to 29C. Dialing them back a bit with a dimmer slows down the rate at which they warm up, keeping the resistor bodies below 80C.

I've calculated the R values to allow rated dissipation in the resistors (25W) at about 90% of line voltage because even when the dimmer is wide open, the dimmer only delivers about 90% of the line voltage. If I didn't calculate the R values for 90% of line voltage, they could not get enough voltage to come to their rated 25W dissipation.

You could build this without the dimmer but the R values would change. For 240V, each resistor should be 2.3k ohms. For 120V, each should be 576 ohms.

Quote:

isnt there different wiring for the fan and the heating and cooling elements on the thermostat? im guessing if im using a fan with a filter on the end i would wire that up on the 'fan' option on the thermostat and have the button switched to 'on' not auto or off, correct?

I'm not sure I understand your question. The fans are wired to run at all times that the unit is plugged in. Only the resistors are switched on and off by the thermostat.

Keep in mind that the thermostat you use must either have a remote mountable thermistor (temperature sensor) or you have to modify the thermostat by removing the thermistor and extending its leads so you can mount the thermistor in the warm air stream while being able to mount the thermostat unit itself on the outside of the dryer unit.

Al B. Fuct · #**167** 08-20-2008, 01:53 AM

Rats, the heat sink I pictured in the above post would not be the best choice. The fins run in the wrong direction. If you put a muffin fan in the middle of the pictured unit, the fins on the ends of the unit will be 'lazy' and won't warm air that is being drawn through the fan. The heatsink I used has fins running on the long axis, so air being pulled through all fins is being heated.

This Jaycar sink (actually 2 of them pictured) would work better. The fan goes on the end of the two stacked sinks. The resistors could be mounted 3 per sink.

LoudBlunts · #**168** 08-20-2008, 08:15 AM

im not understanding where i would put the fan on that heatsink....

nor am i able to find a heatsink like that in the US..... you know im trouble al, but forgive me....could you possibly help me find a heatsink from a US retailer? also the smallest heatsink possible!

and if i understand you correctly....since you are calculating the heatsink i can do without the dimmers? and as long as they are 576 ohms @ 120v correct?

as far the fan question and the thermostat....i know you are supposed to have the fans running the whole time the bud box is drying or plugged in. i just wanted to use the on and off features for the thermostat?

and also you say that the only thing switched on and off by the thermostat is the resistors (excuse me, you'll have to hold my hand as im not looking at one right now)

how does it hook up? is that just on a basic thermostat, b/c i thought thermostat would have contact hookups for the options of 'fan-auto/on/off' -- the heating & the cooling contact hookups right?

if you are still following me, that is where my last question came in at.... like if i wanted to hook all the fans to the thermostat and when i press off all the fans turn off? or it doesnt work like that?