On 14/07/2016 22:19, Cursitor Doom wrote:
On Thu, 14 Jul 2016 21:46:53 +0100, Lee wrote:

It might be interesting to see if you have the same problem with an
ICM7555, but it's much easier just to add the cap, as suggested

Quite! And I shall certainly do so first thing tomorrow. IF it works it
will highlight an astonishing and appalling omission from the datasheet
IMHO.


IMO, The problem isn't so much the omission from the LM317 datasheet,
it's more an omission from the NE555 one.

Interestingly the ICM7555 datasheet says:
"The ICM7555 and ICM7556 devices are, in most instances,
direct replacements for the SE/NE 555/556 devices. However,
it is possible to effect economies in the external component
count using the ICM7555 and ICM7556. Because the bipolar
SE/NE 555/556 devices produce large crowbar currents in the
output driver, it is necessary to decouple the power supply
lines with a good capacitor close to the device. The ICM7555
and ICM7556 devices produce no such transients"