fan kontrol devresi

Low Drop-Out Regulators
A major drawback of the 317T and similar standard regulators is that 1.7–2 volt is lost from the 12v supply, so the fan can only run up to about 85% of its full speed and flow rating. Although this site is aimed at keeping noise down, there may be occasions when you want to turn the wick right up.

You can get much nearer the 12v input with the newer low-dropout regulators, and with the controller shown below my voltage loss running a 200mA (2.4W) fan was only 130mV (12v in, 11.87v out, 99% full speed!).

They cost a fair bit more than the humble 317T – Rapid Electronics price for a MIC29152 is £3.10 compared to 38p for a 317T – but when you factor in the other parts, especially with a fancy control knob, it's not such a big difference overall, and well worth it IMHO.

I've used Micrel's MIC29152BT regulator, which is rated at 1.5A and comes in a 5-pin TO-220 case. If you need more current, the MIC29302BT is identical but rated to 3A, or the similar MIC29502BT will carry 5A. You may need a bigger heat-sink with the bigger boys. See the heat-sink page for the details.

Unlike the 317, the Reference Voltage is across R2, not R1, and the calculated voltage output is

Vout = 1.24(1 + [R1 + VR1] / R2)
With the resistors shown, the calculated output range works out at 6.9v to 12.5v, giving a bit of headroom if component tolerances run the wrong way. (The 20% tolerance band on pots can play havoc with calculations – if your "10k" pot is below about 9k you won't get the full potential. The ratio of (R1+VR1):R2 must be over 8.7:1 – increase R1 to 12k or reduce R2 to 2k)

The two capacitors ensure stability, particularly useful with long supply leads. Some alternative resistors are given below to suit different minimum voltages.

Construction
Parts List
Reg1 MIC29152BT
C1 100n (0.1uF) 16v ceramic
C2 10uF 16v aluminium electrolytic
R1 10k 0.25W 5% or better (see below)
R2 2k2 0.25W 5% or better (see below)
VR1 10k lin pot, 16mm pcb mounting (see below)
Misc TO220 heat-sink (20–25degC/W) & paste, control knob

The stripboard is 7 rows x 14 columns, two track breaks as shown in red. Bend the regulator leads carefully. I found the best way was to support the outer legs as near the case as possible with a thumb-nail and bend outwards slightly, then support again on the other side (I use a dart tip, also very useful for curling resistor or diode leads for vertical mounting) and bend in to fit. The 2 & 4 leads need less bend, again support with a dart or fine screwdriver. Test for fit in the stripboard and fasten on the heatsink.

R1 VR1 R2 Min output Max output
0 10k 1k 1.24v 13.6v
4k7 10k 1k5 5.1v 13.4v
6k8 10k 1k8 5.9v 12.8v
8k2 10k 2k 6.3v 12.5v
10k 10k 2k2 6.9v 12.5v
0 47k 5k1 1.24v 12.7v
18k 47k 6k8 4.5v 13.1v
33k 47k 8k2 6.2v 13.3v
47k 47k 10k 7.1v 12.9v
43k 50k 10k 6.6v 12.7v
Dry-run assemble the components to ensure nothing fouls on the potentiometer or heat-sink, then make the track breaks and solder up, lowest components (links) first, finishing with the regulator. Check carefully, especially for any solder bridges; a multimeter with buzzer continuity check is handy for this, or a magnifying glass.

You can use a range of other resistors in the R1–VR1–R2 chain to give different minimum outputs, or to suit available potentiometers; some examples are given in the table right, or you can work your own values out using the above formula. It's no problem using 100k or 470k pots, just multiply each resistor by 10. For the minimum output, 1.24v, use a wire link instead of R1.

Of course, you won't get over 12v output from a 12v supply, but the headroom allows for some component tolerance.

This regulator can also be used with high-value NTC thermistors in a thermal controller, using the thermistor in place of R2 and a suitable pre-set potentiometer for VR1. For a 100k @25°C thermistor (Maplin CR05F), R1+VR1 set to 470k would give outputs of 5.8v at 20°C, 7v at 25°C, 9v at 31°C and full-speed at 37°C, so R1=430k, VR1=100k would be on the button for fine tuning.

If you want to check different thermistors, there's an Excel spreadsheet download for the L200 regulator that can be adapted, with the complex formula shown here incorporated.

işte arkadaşlar devre burda total maaliyeti taş çatlasın 5 milyon
niye 35 dolar veresinizki 5.25 çıkışlara monte edin fanı ayarlayın bitsin
resimleri yüklemeyi öğrenebilirsem ekleyeceğğim
herkese kolay gelsin.....

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