Or a dual transistor in one package?? That would be about the best they could be matched.?Jim Ford?Sent from my T-Mobile 4G LTE Device
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-------- Original message --------From: "Roger Evans via groups.io" <very_fuzzy_logic@...> Date: 3/3/22 9:02 AM (GMT-08:00) To:
[email protected] Subject: Re: [TekScopes] 7904 power supply repair Morris,You will not do any harm by using two separate transistors but depending how well the two Vbe are matched you will get an output which is not precisely +15V and since you have only one adjustment for all the low voltages you will not get them all spot on at the same time.? You also have the differential drift with temperature which means the +15V will change as the scope warms up.How much this matters in practice depends on how well matched are your discrete devices, how well you clamp them together for thermal matching and how tolerant you are on changes in calibration.? I would be very tempted to match up a pair from a batch of 10 or so, clamp them with some brass or aluminium strip and just try it out.? Costs very little and you may find you have an adequate solution for your needs.Roger
