I'm looking for advise on what transistor to buy - something general purpose, low to medium power, does not matter through hole or SMD. Apparently I've used up all the NPNs (BD135) I had and only two PNPs (BD140) left.. Possibly will order a couple of dozens at RS components to put this matter to rest once and for all :-))
On PNP side choice is easy - BD140 cost £0.15 in a pack of 10 (1.5 amp), but I'm open to try out something new.
part
price
current(A)
dissipation(W)
2N5087
£0.178
0.05
0.625
BD140
£0.15
1.5
1.25*
TIP127
£0.326
5
65
On NPN side things become more complicated - more choice.
part
price
current(A)
dissipation(W)
2N5088
£0.20
0.05
n/a
2n2222
£0.24
0.6
0.625
2N4401
£0.057
0.6
0.625
ZTX450
£0.40
1
1
ZTX550
£0.424
1
1
ZTX851
£0.856
5
1.2
BD135
£0.26
3
1.25*
BD139
£0.116
3
1.25*
TIP120
£0.425
5
65
TIP122
£0.39
8 (nice!)
65
*without heatsink
TIP120, TIP122 and TIP127 are darlingtons.
N-mosfets:
part
price
R(ohm)
current(A)
dissipation(W)
IRLR3717
£1.012
0.004
120
89
IRLS3036
£3.87
0.0019
240
320
IRLB8743
£0.608
0.003
150
140
IRL520
£0.66
0.18
10
48
2n2222 does not seem to be costefficient in comparison...
So fare a good combination seem to be twenty BD139 and a ten TIP122.
Edit: Will update tables as component suggestions come in.
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You really have to pay attention to what your circuit demands for the maximum voltage, current, power, gain/hfe and frequency.
I often use these:
TIP122 NPN DAR
TIP127 PNP DAR
2N5088 NPN General Purpose Amplifier
2N5087 PNP General Purpose Amplifier
IRL520 Power MOSFET N channel
If the transistor is going to be used in simple switched on/off mode (as most arduino projects do) rather then any analog projects, the selection can be on the most economical ones assuming their max voltage and current datasheet specs are honored.
ZTX450 / ZTX452 / ZTX550 / ZTX551 - low saturation voltage e-line devices
ZTX851 - amazing NPN switching transistor handles pulses to 20A in e-line package!
spolt for choice with MOSFETs but any logic level device with Rds(on) < 0.01 ohms and
40V or more Vds is worth considering (less than 0.03 ohms if p-channel)
For silly MOSFETs the IRLR3717 is 4 milliohm 20V, DPAK SMD,
IRLS3036 is 2 milliohm, 60V, in a whacky 7-pin surface mount D2PAK
variant. That will carry 15A without any heatsinking and 100A with
25W worth of heatsinking...
Thank you Larry, added that one to my shopping list!
retrolefty:
If the transistor is going to be used in simple switched on/off mode (as most arduino projects do) rather then any analog projects, the selection can be on the most economical ones assuming their max voltage and current datasheet specs are honored.
Lefty
Yep, that's the plan! Though will use the beefier once on output of a digipot - got a satisfactory result few hours ago, but will try a mosfet in this role later on today as well.
MarkT:
ZTX851 - amazing NPN switching transistor handles pulses to 20A in e-line package!
IRLS3036 is 2 milliohm, 60V, in a whacky 7-pin surface mount D2PAK variant.
IRLS3036 is an ultimate bad boy - in its price range.
ZTX851 really is a little miracle. Package is very much like TO92, but with only half the thermal resistance (100C/W vs 200C/W). Operating temperature is 200C against usual 150C. Together that effectively doubles the load they can handle!
Man you rock, thanks!
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