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I always having this problem when trying to convert my prototype design (which usually built using normal discrete through-hole electronic components) to surface-mount (SMD) version for size-shrinking & mass-production.

I always have difficult time to find a substitution/replacement model for the SMD side. Anyone here have any good resource/website which can direct me to find SMD replacement for diodes & transistors?

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What Oli says, BUT BC337-40 (NPN) and BC327-40 (PNP) through hole TO92 transistors will meet 95% of your small transistor needs, and they have the direct equivalents of BC817 / BC807. The SMD versions are available in Asia as Leshan Radio parts (NPN & PNP through hole and SMD) with similar part numbers - LRC817, LRC807. These are genuine Motorola mask parts made by a joint venture company between Motorola and LR. They have a range of older lower tech Motorola parts plus their own parts as well. Some of their own parts are very useful.

LR transistors page 1/3

For larger wattages, higher voltage or current, low noise high FT etc search Digikey [As trav1s suggests] for "transistor" follow the yellow brick road (menu selections) to the relevant selector guide and enter required parameters. Digikey transistors end of yellow brick road is here . Then sort by price and choose the cheapest in stock at the required volume - or use this as a guide to buy elsewhere. Consider using only ROHS compliant parts.

If a part is too special to succumb to these methods, ask us here with a specific design question.

Taiwanese CETSEMI also make some extremely nice transistors and small MOSFETs. The CETSemi CES2310 will do most things that an amateur would expect a SOT23 N Channel MOSFET to do.


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  • \$\begingroup\$ I was surprised when I learned how much power the BC337 can tolerate in its TO-92 package. \$\endgroup\$ – starblue Sep 28 '12 at 16:28
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The matter of substitution of a component is driven by the requirements of the circuit and hence the necessary specs of the component, so knowing these you would go to somewhere like Farnell or Mouser and use the parametric searches to find suitable replacements.

If you are doing this regularly you need to learn how to decide on a suitable replacement using the datasheet - if it's just a one off and you need help swapping a couple of components then let us know what they are and a replacement can be advised on - plus the process of selecting one can also be detailed as this should prove instructive.

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